diff --git a/versions/3.2.0.md b/versions/3.2.0.md
index 67d90142b5..429bebe074 100644
--- a/versions/3.2.0.md
+++ b/versions/3.2.0.md
@@ -10,7 +10,11 @@ This document is licensed under [The Apache License, Version 2.0](https://www.ap
 
 The OpenAPI Specification (OAS) defines a standard, language-agnostic interface to HTTP APIs which allows both humans and computers to discover and understand the capabilities of the service without access to source code, documentation, or through network traffic inspection. When properly defined, a consumer can understand and interact with the remote service with a minimal amount of implementation logic.
 
-An OpenAPI definition can then be used by documentation generation tools to display the API, code generation tools to generate servers and clients in various programming languages, testing tools, and many other use cases.
+An OpenAPI description can then be used by documentation generation tools to display the API, code generation tools to generate servers and clients in various programming languages, testing tools, and many other use cases.
+
+For examples of OpenAPI usage and additional documentation, please visit [learn.openapis.org](https://learn.openapis.org/).
+
+For extension registries and other specifications published by the OpenAPI Initiative, as well as the authoritative rendering of this specification, please visit [spec.openapis.org](https://spec.openapis.org/).
 
 ## Table of Contents
 <!-- TOC depthFrom:1 depthTo:3 withLinks:1 updateOnSave:1 orderedList:0 -->
@@ -71,6 +75,12 @@ An OpenAPI definition can then be used by documentation generation tools to disp
 ##### <a name="oasDocument"></a>OpenAPI Document
 A self-contained or composite resource which defines or describes an API or elements of an API. The OpenAPI document MUST contain at least one [paths](#pathsObject) field, a [components](#oasComponents) field or a [webhooks](#oasWebhooks) field. An OpenAPI document uses and conforms to the OpenAPI Specification.
 
+##### <a name="definitionsSchema"></a>Schema
+
+A "schema" is a formal description of syntax and structure.
+This document serves as the [schema](#schema) for the OpenAPI Specification format; a non-authoritative JSON Schema based on this document is also provided on [spec.openapis.org](https://spec.openapis.org) for informational purposes.
+This specification also _uses_ schemas in the form of the [Schema Object](#schemaObject).
+
 ##### <a name="pathTemplating"></a>Path Templating
 Path templating refers to the usage of template expressions, delimited by curly braces ({}), to mark a section of a URL path as replaceable using path parameters.
 
@@ -99,6 +109,11 @@ Some examples of possible media type definitions:
 The HTTP Status Codes are used to indicate the status of the executed operation. 
 The available status codes are defined by [RFC7231](https://tools.ietf.org/html/rfc7231#section-6) and registered status codes are listed in the [IANA Status Code Registry](https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml).
 
+##### <a name="httpAndCaseSensitivity"></a>HTTP and Case Sensitivity
+
+As most field names and values in the OpenAPI Specification are case-sensitive, this document endeavors to call out any case-insensitive names and values.
+However, the case sensitivity of field names and values that map directly to HTTP concepts follow the case sensitivity rules of HTTP, even if this document does not make a note of every concept.
+
 ##### <a name="undefinedAndImplementationDefinedBehavior"></a>Undefined and Implementation-Defined Behavior
 
 This specification deems certain situations to have either _undefined_ or _implementation-defined_ behavior.
@@ -120,11 +135,11 @@ The OpenAPI Specification is versioned using a `major`.`minor`.`patch` versionin
 
 Occasionally, non-backwards compatible changes may be made in `minor` versions of the OAS where impact is believed to be low relative to the benefit provided.
 
-An OpenAPI document compatible with OAS 3.\*.\* contains a required [`openapi`](#oasVersion) field which designates the version of the OAS that it uses.
+An OpenAPI description document compatible with OAS 3.\*.\* contains a required [`openapi`](#oasVersion) field which designates the version of the OAS that it uses.
 
 ### Format
 
-An OpenAPI document that conforms to the OpenAPI Specification is itself a JSON object, which may be represented either in JSON or YAML format.
+An OpenAPI description document that conforms to the OpenAPI Specification is itself a JSON object, which may be represented either in JSON or YAML format.
 
 For example, if a field has an array value, the JSON array representation will be used:
 
@@ -136,25 +151,99 @@ For example, if a field has an array value, the JSON array representation will b
 All field names in the specification are **case sensitive**.
 This includes all fields that are used as keys in a map, except where explicitly noted that keys are **case insensitive**.
 
-The schema exposes two types of fields: Fixed fields, which have a declared name, and Patterned fields, which declare a regex pattern for the field name.
+The [schema](#schema) exposes two types of fields: Fixed fields, which have a declared name, and Patterned fields, which declare a regex pattern for the field name.
 
 Patterned fields MUST have unique names within the containing object. 
 
 In order to preserve the ability to round-trip between YAML and JSON formats, YAML version [1.2](https://yaml.org/spec/1.2/spec.html) is RECOMMENDED along with some additional constraints:
 
-- Tags MUST be limited to those allowed by the [JSON Schema ruleset](https://yaml.org/spec/1.2/spec.html#id2803231).
+- Tags MUST be limited to those allowed by [YAML's JSON schema ruleset](https://yaml.org/spec/1.2/spec.html#id2803231), which defines a subset of the YAML syntax and is unrelated to [JSON Schema](https://tools.ietf.org/html/draft-bhutton-json-schema-00).
 - Keys used in YAML maps MUST be limited to a scalar string, as defined by the [YAML Failsafe schema ruleset](https://yaml.org/spec/1.2/spec.html#id2802346).
 
-**Note:** While APIs may be defined by OpenAPI documents in either YAML or JSON format, the API request and response bodies and other content are not required to be JSON or YAML.
+**Note:** While APIs may be described by OpenAPI documents in either YAML or JSON format, the API request and response bodies and other content are not required to be JSON or YAML.
 
 ### <a name="documentStructure"></a>Document Structure
 
-An OpenAPI document MAY be made up of a single document or be divided into multiple, connected parts at the discretion of the author. In the latter case, [`Reference Objects`](#referenceObject) and [`Schema Object`](#schemaObject) `$ref` keywords are used.
+An OpenAPI Description (OAD) MAY be made up of a single document or be divided into multiple, connected parts at the discretion of the author. In the latter case, [Reference Object](#referenceObject), [Path Item Object](#pathItemObject) and [Schema Object](#schemaObject) `$ref` keywords, as well as the [Link Object](#linkObject) `operationRef` keyword, are used.
+
+Any document consisting entirely of an OpenAPI Object is known as a **complete OpenAPI document**.
+In a multi-document description, the document containing the [OpenAPI Object](#oasObject) where parsing begins for a specific API's description is known as that API's **entry OpenAPI document**, or simply **entry document**.
 
 It is RECOMMENDED that the root OpenAPI document be named: `openapi.json` or `openapi.yaml`.
 
+#### <a name="parsingDocuments"></a>Parsing Documents
+
+In order to properly handle [Schema Objects](#schemaObject), OAS 3.1 inherits the parsing requirements of [JSON Schema draft 2020-12 §9](https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#section-9), with appropriate modifications regarding base URIs as specified in [Relative References In URIs](#relativeReferencesURI).
+
+This includes a requirement to parse complete documents before deeming a Schema object reference to be unresolvable, in order to detect keywords that might provide the reference target or impact the determination of the appropriate base URI.
+
+Implementations MAY support complete-document parsing in any of the following ways:
+
+* Detecting OpenAPI or JSON Schema documents using media types
+* Detecting OpenAPI documents through the root `openapi` property
+* Detecting JSON Schema documents through detecting keywords or otherwise successfully parsing the document in accordance with the JSON Schema specification
+* Detecting a document containing a referenceable Object at its root based on the expected type of the reference
+* Allowing users to configure the type of documents that might be loaded due to a reference to a non-root Object
+
+Implementations that parse referenced fragments of OpenAPI content without regard for the content of the rest of the containing document will miss keywords that change the meaning and behavior of the reference target.
+In particular, failing to take into account keywords that change the base URI introduces security risks by causing references to resolve to unintended URIs, with unpredictable results.
+While some implementations support this sort of parsing due to the requirements of past versions of this specification, in version 3.1, the result of parsing fragments in isolation is _undefined_ and likely to contradict the requirements of this specification.
+
+While it is possible to structure certain OpenAPI Descriptions to ensure that they will behave correctly when references are parsed as isolated fragments, depending on this is NOT RECOMMENDED.
+This specification does not explicitly enumerate the conditions under which such behavior is safe, and provides no guarantee for continued safety in any future versions of the OAS.
+
+A special case of parsing fragments of OAS content would be if such fragments are embedded in another format, referred to as an _embedding format_ with respect to the OAS.
+Note that the OAS itself is an embedding format with respect to JSON Schema, which is embedded as Schema Objects.
+It is the responsibility of an embedding format to define how to parse embedded content, and OAS implementations that do not document support for an embedding format cannot be expected to parse embedded OAS content correctly.
+
+#### <a name="structuralInteroperability"></a>Structural Interoperability
+
+When parsing an OAD, JSON or YAML objects are parsed into specific Objects (such as [Operation Objects](#operationObject), [Response Objects](#responseObject), [Reference Objects](#referenceObject), etc.) based on the parsing context.  Depending on how references are arranged, a given JSON or YAML object can be parsed in multiple different contexts:
+
+* As a complete OpenAPI Description document
+* As the Object type implied by its parent Object within the document
+* As a reference target, with the Object type matching the reference source's context
+
+If the same JSON/YAML object is parsed multiple times and the respective contexts require it to be parsed as _different_ Object types, the resulting behavior is _implementation defined_, and MAY be treated as an error if detected.  An example would be referencing an empty Schema Object under `#/components/schemas` where a Path Item Object is expected, as an empty object is valid for both types.  For maximum interoperability, it is RECOMMENDED that OpenAPI Description authors avoid such scenarios.
+
 #### <a name="resolvingImplicitConnections"></a>Resolving Implicit Connections
 
+Several features of this specification require resolution of non-URI-based connections to some other part of the OpenAPI Description (OAD).
+
+These connections are unambiguously resolved in single-document OADs, but the resolution process in multi-document OADs is _implementation-defined_, within the constraints described in this section.
+In some cases, an unambiguous URI-based alternative is available, and OAD authors are RECOMMENDED to always use the alternative:
+
+Source | Target | Alternative
+------ | ------ | -----------
+[Security Requirement Object](#securityRequirementObject) `{name}` |  [Security Scheme Object](#securitySchemeObject) name under the [Components Object](#componentsObject) | _n/a_
+[Discriminator Object](#discriminatorObject) `mapping` _(implicit, or explicit name syntax)_ | [Schema Object](#schemaObject) name under the Components Object | `mapping` _(explicit URI syntax)_
+[Operation Object](#operationObject) `tags` | [Tag Object](#tagObject) `name` (in the Components Object) | _n/a_
+[Link Object](#linkObject) `operationId` | [Path Item Object](#pathItemObject) `operationId` | `operationRef`
+
+A fifth implicit connection involves appending the templated URL paths of the [Paths Object](#pathsObject) to the appropriate [Server Object](#serverObject)'s `url` field.
+This is unambiguous because only the entry document's Paths Object contributes URLs to the described API.
+
+It is RECOMMENDED to consider all Operation Objects from all parsed documents when resolving any Link Object `operationId`.
+This requires parsing all referenced documents prior to determining an `operationId` to be unresolvable.
+
+The implicit connections in the Security Requirement Object and Discriminator Object rely on the _component name_, which is the property name holding the component in the appropriately typed sub-object of the Components Object.
+For example, the component name of the Schema Object at `#/components/schemas/Foo` is `Foo`.
+The implicit connection of `tags` in the Operation Object uses the `name` field of Tag Objects, which (like the Components Object) are found under the root OpenAPI Object.
+This means resolving component names and tag names both depend on starting from the correct OpenAPI Object.
+
+For resolving component and tag name connections from a referenced (non-entry) document, it is RECOMMENDED that tools resolve from the entry document, rather than the current document.
+This allows Security Scheme Objects and Tag Objects to be defined with the API's deployment information (the top-level Server Objects), and treated as an interface for referenced documents to access.
+
+The interface approach can also work for Discriminator Objects and Schema Objects, but it is also possible to keep the Discriminator Object's behavior within a single document using the relative URI-reference syntax of `mapping`.
+
+There are no URI-based alternatives for the Security Requirement Object or for the Operation Object's `tags` field.
+These limitations are expected to be addressed in a future release.
+
+See [Security Requirement in a Referenced Document](#security-requirement-in-a-referenced-document) for an example of the possible resolutions, including which one is recommended by this section.
+The behavior for Discrimator Object non-URI mappings and for the Operation Object's `tags` field operate on the same principles.
+
+Note that no aspect of implicit connection resolution changes how [URIs are resolved](#relativeReferencesURI), or restricts their possible targets.
+
 ### <a name="dataTypes"></a>Data Types
 
 Data types in the OAS are based on the types supported by the [JSON Schema Specification Draft 2020-12](https://tools.ietf.org/html/draft-bhutton-json-schema-00#section-4.2.1).
@@ -163,7 +252,9 @@ Models are defined using the [Schema Object](#schemaObject), which is a superset
 
 <a name="dataTypeFormat"></a>As defined by the [JSON Schema Validation specification](https://tools.ietf.org/html/draft-bhutton-json-schema-validation-00#section-7.3), data types can have an optional modifier property: `format`.  As described in that specification, `format` is treated as a non-validating annotation by default; the ability to validate `format` varies across implementations.
 
-OAS defines additional formats to provide fine detail for primitive data types.
+The OpenAPI Initiative also hosts a [Format Registry](https://spec.openapis.org/registry/format/) for formats defined by OAS users and other specifications.  Support for any registered format is strictly OPTIONAL, and support for one registered format does not imply support for any others.
+
+Types that are not accompanied by a `format` property follow the type definition in the JSON Schema. Tools that do not recognize a specific `format` MAY default back to the `type` alone, as if the `format` is not specified.
 
 The formats defined by the OAS are:
 
@@ -213,25 +304,45 @@ OAS < 3.1 | OAS 3.1+ | Comments
 
 ### <a name="richText"></a>Rich Text Formatting
 Throughout the specification `description` fields are noted as supporting CommonMark markdown formatting.
-Where OpenAPI tooling renders rich text it MUST support, at a minimum, markdown syntax as described by [CommonMark 0.27](https://spec.commonmark.org/0.27/). Tooling MAY choose to ignore some CommonMark features to address security concerns. 
+Where OpenAPI tooling renders rich text it MUST support, at a minimum, markdown syntax as described by [CommonMark 0.27](https://spec.commonmark.org/0.27/). Tooling MAY choose to ignore some CommonMark or extension features to address security concerns. 
+
+While the framing of CommonMark 0.27 as a minimum requirement means that tooling MAY choose to implement extensions on top of it, note that any such extensions are by definition implementation-defined and will not be interoperable.
+OpenAPI Description authors SHOULD consider how text using such extensions will be rendered by tools that offer only the minimum support.
 
-### <a name="relativeReferencesURI"></a>Relative References in URIs
+
+### <a name="relativeReferencesURI"></a>Relative References in API Description URIs
+
+URIs used as references within an OpenAPI Description, or to external documentation or other supplementary information such as a license, are resolved as _identifiers_, and described by this specification as ***URIs***.
+As noted under [Parsing Documents](#parsingDocuments), this specification inherits JSON Schema draft 2020-12's requirements for loading documents and associating them with their expected URIs, which might not match their current location.
+This feature is used both for working in development or test environments without having to change the URIs, and for working within restrictive network configurations or security policies.
+
+Note that some URI fields are named `url` for historical reasons, but the descriptive text for those fields uses the correct "URI" terminology.
 
 Unless specified otherwise, all properties that are URIs MAY be relative references as defined by [RFC3986](https://tools.ietf.org/html/rfc3986#section-4.2).
 
-Relative references, including those in [`Reference Objects`](#referenceObject), [`PathItem Object`](#pathItemObject) `$ref` fields, [`Link Object`](#linkObject) `operationRef` fields and [`Example Object`](#exampleObject) `externalValue` fields, are resolved using the referring document as the Base URI according to [RFC3986](https://tools.ietf.org/html/rfc3986#section-5.2).
+Relative references in [`Schema Objects`](#schemaObject), including any that appear as `$id` values, use the nearest parent `$id` as a Base URI, as described by [JSON Schema Specification Draft 2020-12](https://tools.ietf.org/html/draft-bhutton-json-schema-00#section-8.2).
+
+Relative URI references in other Objects, and in Schema Objects where no parent schema contains an `$id`, MUST be resolved using the referring document's base URI, which is determined in accordance with [RFC3986 §5.1.2 – 5.1.4](https://tools.ietf.org/html/rfc3986#section-5.1.2).
+In practice, this is usually the retrieval URI of the document, which MAY be determined based on either its current actual location or a user-supplied expected location.
 
 If a URI contains a fragment identifier, then the fragment should be resolved per the fragment resolution mechanism of the referenced document.  If the representation of the referenced document is JSON or YAML, then the fragment identifier SHOULD be interpreted as a JSON-Pointer as per [RFC6901](https://tools.ietf.org/html/rfc6901).
 
-Relative references in [`Schema Objects`](#schemaObject), including any that appear as `$id` values, use the nearest parent `$id` as a Base URI, as described by [JSON Schema Specification Draft 2020-12](https://tools.ietf.org/html/draft-bhutton-json-schema-00#section-8.2).  If no parent schema contains an `$id`, then the Base URI MUST be determined according to [RFC3986](https://tools.ietf.org/html/rfc3986#section-5.1).
+### <a name="relativeReferencesURL"></a>Relative References in API URLs
 
-### <a name="relativeReferencesURL"></a>Relative References in URLs
+API endpoints are by definition accessed as locations, and are described by this specification as ***URLs***.
 
 Unless specified otherwise, all properties that are URLs MAY be relative references as defined by [RFC3986](https://tools.ietf.org/html/rfc3986#section-4.2).
 Unless specified otherwise, relative references are resolved using the URLs defined in the [`Server Object`](#serverObject) as a Base URL. Note that these themselves MAY be relative to the referring document.
 
+Relative references in CommonMark hyperlinks are resolved in their rendered context, which might differ from the context of the API description.
+
 ### Schema
 
+This section describes the structure of the OpenAPI Description format.
+This text is the only normative description of the format.
+A JSON Schema is hosted on [spec.openapis.org](https://spec.openapis.org) for informational purposes.
+If the JSON Schema differs from this section, then this section MUST be considered authoritative.
+
 In the following description, if a field is not explicitly **REQUIRED** or described with a MUST or SHALL, it can be considered OPTIONAL.
 
 #### <a name="oasObject"></a>OpenAPI Object
@@ -268,10 +379,10 @@ Field Name | Type | Description
 <a name="infoTitle"></a>title | `string` | **REQUIRED**. The title of the API.
 <a name="infoSummary"></a>summary | `string` | A short summary of the API.
 <a name="infoDescription"></a>description | `string` | A description of the API. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
-<a name="infoTermsOfService"></a>termsOfService | `string` | A URL to the Terms of Service for the API. This MUST be in the form of a URL.
+<a name="infoTermsOfService"></a>termsOfService | `string` | A URI for the Terms of Service for the API. This MUST be in the form of a URI.
 <a name="infoContact"></a>contact | [Contact Object](#contactObject) | The contact information for the exposed API.
 <a name="infoLicense"></a>license | [License Object](#licenseObject) | The license information for the exposed API.
-<a name="infoVersion"></a>version | `string` | **REQUIRED**. The version of the OpenAPI document (which is distinct from the [OpenAPI Specification version](#oasVersion) or the API implementation version).
+<a name="infoVersion"></a>version | `string` | **REQUIRED**. The version of the OpenAPI document (which is distinct from the [OpenAPI Specification version](#oasVersion) or the version of the API being described).
 
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
@@ -321,7 +432,7 @@ Contact information for the exposed API.
 Field Name | Type | Description
 ---|:---:|---
 <a name="contactName"></a>name | `string` | The identifying name of the contact person/organization.
-<a name="contactUrl"></a>url | `string` | The URL pointing to the contact information. This MUST be in the form of a URL.
+<a name="contactUrl"></a>url | `string` | The URI for to the contact information. This MUST be in the form of a URI.
 <a name="contactEmail"></a>email | `string` | The email address of the contact person/organization. This MUST be in the form of an email address.
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
@@ -352,7 +463,7 @@ Field Name | Type | Description
 ---|:---:|---
 <a name="licenseName"></a>name | `string` | **REQUIRED**. The license name used for the API.
 <a name="licenseIdentifier"></a>identifier | `string` | An [SPDX](https://spdx.org/spdx-specification-21-web-version#h.jxpfx0ykyb60) license expression for the API. The `identifier` field is mutually exclusive of the `url` field.
-<a name="licenseUrl"></a>url | `string` | A URL to the license used for the API. This MUST be in the form of a URL. The `url` field is mutually exclusive of the `identifier` field.
+<a name="licenseUrl"></a>url | `string` | A URI for the license used for the API. This MUST be in the form of a URI. The `url` field is mutually exclusive of the `identifier` field.
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
 
@@ -1035,7 +1146,7 @@ Allows referencing an external resource for extended documentation.
 Field Name | Type | Description
 ---|:---:|---
 <a name="externalDocDescription"></a>description | `string` | A description of the target documentation. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
-<a name="externalDocUrl"></a>url | `string` | **REQUIRED**. The URL for the target documentation. This MUST be in the form of a URL.
+<a name="externalDocUrl"></a>url | `string` | **REQUIRED**. The URI for the target documentation. This MUST be in the form of a URI.
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
 
@@ -1059,6 +1170,8 @@ Describes a single operation parameter.
 
 A unique parameter is defined by a combination of a [name](#parameterName) and [location](#parameterIn).
 
+See [Appendix E](#percentEncodingAndFormMediaTypes) for a detailed examination of percent-encoding concerns, including interactions with the `application/x-www-form-urlencoded` query string format.
+
 ##### Parameter Locations
 There are four possible parameter locations specified by the `in` field:
 * path - Used together with [Path Templating](#pathTemplating), where the parameter value is actually part of the operation's URL. This does not include the host or base path of the API. For example, in `/items/{itemId}`, the path parameter is `itemId`.
@@ -1066,11 +1179,11 @@ There are four possible parameter locations specified by the `in` field:
 * header - Custom headers that are expected as part of the request. Note that [RFC7230](https://tools.ietf.org/html/rfc7230#page-22) states header names are case insensitive.
 * cookie - Used to pass a specific cookie value to the API.
 
-
 ##### Fixed Fields
 
 The rules for serialization of the parameter are specified in one of two ways.
 Parameter Objects MUST include either a `content` field or a `schema` field, but not both.
+See [Appendix B](#dataTypeConversion) for a discussion of converting values of various types to string representations.
 
 ###### Common Fixed Fields
 
@@ -1083,25 +1196,35 @@ Field Name | Type | Description
 <a name="parameterDescription"></a>description | `string` | A brief description of the parameter. This could contain examples of use. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
 <a name="parameterRequired"></a>required | `boolean` | Determines whether this parameter is mandatory. If the [parameter location](#parameterIn) is `"path"`, this property is **REQUIRED** and its value MUST be `true`. Otherwise, the property MAY be included and its default value is `false`.
 <a name="parameterDeprecated"></a> deprecated | `boolean` | Specifies that a parameter is deprecated and SHOULD be transitioned out of usage. Default value is `false`.
-<a name="parameterAllowEmptyValue"></a> allowEmptyValue | `boolean` | If `true`, clients MAY pass a zero-length string value in place of parameters that would otherwise be omitted entirely, which the server SHOULD interpret as the parameter being unused. Default value is `false`. If [`style`](#parameterStyle) is used, and if behavior is `n/a` (cannot be serialized), the value of `allowEmptyValue` SHALL be ignored. Interactions between this field and the parameter's [Schema Object](#schemaObject) are implementation-defined. This field is valid only for `query` parameters. Use of this property is NOT RECOMMENDED, and it is likely to be removed in a later revision.
+<a name="parameterAllowEmptyValue"></a> allowEmptyValue | `boolean` | If `true`, clients MAY pass a zero-length string value in place of parameters that would otherwise be omitted entirely, which the server SHOULD interpret as the parameter being unused. Default value is `false`. If [`style`](#parameterStyle) is used, and if [behavior is _n/a_ (cannot be serialized)](#style-examples), the value of `allowEmptyValue` SHALL be ignored. Interactions between this field and the parameter's [Schema Object](#schemaObject) are implementation-defined. This field is valid only for `query` parameters. Use of this property is NOT RECOMMENDED, and it is likely to be removed in a later revision.
+
+This object MAY be extended with [Specification Extensions](#specificationExtensions).
+
+Note that while `"Cookie"` as a `name` is not forbidden with `in: header`, the effect of defining a cookie parameter that way is undefined; use `in: cookie` instead.
 
 ###### Fixed Fields for use with `schema`
 
 For simpler scenarios, a [`schema`](#parameterSchema) and [`style`](#parameterStyle) can describe the structure and syntax of the parameter.
-When `example` or `examples` are provided in conjunction with the `schema` object, the example MUST follow the prescribed serialization strategy for the parameter.
+When `example` or `examples` are provided in conjunction with the `schema` object, the example SHOULD match the specified schema and follow the prescribed serialization strategy for the parameter.
+The `example` and `examples` fields are mutually exclusive, and if either is present it SHALL _override_ any `example` in the schema.
+
+Serializing with `schema` is NOT RECOMMENDED for `in: cookie` parameters, `in: header` parameters that use HTTP header parameters (name=value pairs following a `;`) in their values, or `in: header` parameters where values might have non-URL-safe characters; see [Appendix D](#serializingHeadersAndCookies) for details.
 
 Field Name | Type | Description
 ---|:---:|---
 <a name="parameterStyle"></a>style | `string` | Describes how the parameter value will be serialized depending on the type of the parameter value. Default values (based on value of `in`): for `query` - `form`; for `path` - `simple`; for `header` - `simple`; for `cookie` - `form`.
-<a name="parameterExplode"></a>explode | `boolean` | When this is true, parameter values of type `array` or `object` generate separate parameters for each value of the array or key-value pair of the map. For other types of parameters this property has no effect. When [`style`](#parameterStyle) is `form`, the default value is `true`. For all other styles, the default value is `false`.
-<a name="parameterAllowReserved"></a>allowReserved | `boolean` | Determines whether the parameter value SHOULD allow reserved characters, as defined by [RFC3986](https://tools.ietf.org/html/rfc3986#section-2.2) `:/?#[]@!$&'()*+,;=` to be included without percent-encoding. This property only applies to parameters with an `in` value of `query`. The default value is `false`.
+<a name="parameterExplode"></a>explode | `boolean` | When this is true, parameter values of type `array` or `object` generate separate parameters for each value of the array or key-value pair of the map. For other types of parameters this property has no effect. When [`style`](#parameterStyle) is `form`, the default value is `true`. For all other styles, the default value is `false`. Note that despite `false` being the default for `deepObject`, the combination of `false` with `deepObject` is undefined.
+<a name="parameterAllowReserved"></a>allowReserved | `boolean` | When this is true, parameter values are serialized  using reserved expansion, as defined by [RFC6570](https://datatracker.ietf.org/doc/html/rfc6570#autoid-20), which allows [RFC3986's reserved character set](https://datatracker.ietf.org/doc/html/rfc3986#autoid-13), as well as percent-encoded triples, to pass through unchanged, while still percent-encoding all other disallowed characters (including `%` outside of percent-encoded triples). Applications are still responsible for percent-encoding reserved characters that are [not allowed in the query string](https://datatracker.ietf.org/doc/html/rfc3986#autoid-24) (`[`, `]`, `#`), or have a special meaning in `application/x-www-form-urlencoded` (`-`, `&`, `+`); see Appendices [C](#usingRFC6570Implementations) and [E](#percentEncodingAndFormMediaTypes) for details. This property only applies to parameters with an `in` value of `query`. The default value is `false`.
 <a name="parameterSchema"></a>schema | [Schema Object](#schemaObject) | The schema defining the type used for the parameter.
-<a name="parameterExample"></a>example | Any | Example of the parameter's potential value. The example SHOULD match the specified schema and encoding properties if present. The `example` field is mutually exclusive of the `examples` field. Furthermore, if referencing a `schema` that contains an example, the `example` value SHALL _override_ the example provided by the schema. To represent examples of media types that cannot naturally be represented in JSON or YAML, a string value can contain the example with escaping where necessary.
-<a name="parameterExamples"></a>examples | Map[ `string`, [Example Object](#exampleObject) \| [Reference Object](#referenceObject)] | Examples of the parameter's potential value. Each example SHOULD contain a value in the correct format as specified in the parameter encoding. The `examples` field is mutually exclusive of the `example` field. Furthermore, if referencing a `schema` that contains an example, the `examples` value SHALL _override_ the example provided by the schema.
+<a name="parameterExample"></a>example | Any | Example of the parameter's potential value; see [Working With Examples](#working-with-examples).
+<a name="parameterExamples"></a>examples | Map[ `string`, [Example Object](#exampleObject) \| [Reference Object](#referenceObject)] | Examples of the parameter's potential value; see [Working With Examples](#working-with-examples).
 
-###### Fixed Fields and considerations for use with `content`
+See also [Appendix C: Using RFC6570 Implementations](#usingRFC6570Implementations) for additional guidance.
+
+###### Fixed Fields for use with `content`
 
 For more complex scenarios, the [`content`](#parameterContent) property can define the media type and schema of the parameter, as well as give examples of its use.
+Using `content` with a `text/plain` media type is RECOMMENDED for `in: header` and `in: cookie` parameters where the `schema` strategy is not appropriate.
 
 Field Name | Type | Description
 ---|:---:|---
@@ -1121,7 +1244,7 @@ spaceDelimited | `array`, `object` | `query` | Space separated array values or o
 pipeDelimited | `array`, `object` | `query` | Pipe separated array values or object properties and values. This option replaces `collectionFormat` equal to `pipes` from OpenAPI 2.0.
 deepObject | `object` | `query` | Provides a simple way of rendering nested objects using form parameters.
 
-The behavior of applying a style that uses a delimiter to data containing that delimiter is not defined, and is therefore NOT RECOMMENDED.  To ensure interoperability, any such delimiter characters need to be escaped prior to serializing with the style, and unescaped after parsing.  In the case of `spaceDelimited`, care must be taken to avoid confusing interactions with URL parameter encoding of spaces.
+See [Appendix E](#percentEncodingAndFormMediaTypes) for a discussion of percent-encoding, including when delimiters need to be percent-encoded and options for handling collisions with percent-encoded data.
 
 ##### Style Examples
 
@@ -1132,7 +1255,15 @@ Assume a parameter named `color` has one of the following values:
    array -> ["blue","black","brown"]
    object -> { "R": 100, "G": 200, "B": 150 }
 ```
-The following table shows examples of rendering differences for each value.
+
+The following table shows examples, as would be shown with the `example` or `examples` keywords, of the different serializations for each value.
+
+* The value _empty_ denotes the empty string, and is unrelated to the `allowEmptyValue` field
+* The behavior of combinations marked _n/a_ is undefined
+* The `undefined` replaces the `empty` column in previous versions of this specification in order to better align with [RFC6570 §2.3](https://www.rfc-editor.org/rfc/rfc6570.html#section-2.3) terminology, which describes certain values including but not limited to `null` as "undefined" values with special handling; notably, the empty string is _not_ undefined
+* For `form` and the non-RFC6570 query string styles `spaceDelimited`, `pipeDelimited`, and `deepObject`, each example is shown prefixed with `?` as if it were the only query parameter; see [Appendix C](#usingRFC6570Implementations) for more information on constructing query strings from multiple parameters, and [Appendix D](#serializingHeadersAndCookies) for warnings regarding `form` and cookie parameters
+* Note that the `?` prefix is not appropriate for serializing `application/x-www-form-urlencoded` HTTP message bodies, and MUST be stripped or (if constructing the string manually) not added when used in that context; see the [Encoding Object](#encodingObject) for more information
+* The examples are percent-encoded as required by RFC6570 and RFC3986; see [Appendix E](#percentEncodingAndFormMediaTypes) for a thorough discussion of percent-encoding concerns, including why unencoded `|` (`%7C`), `[` (`%5B`), and `]` (`%5D`) seem to work in some environments despite not being compliant.
 
 [`style`](#styleValues) | `explode` | `empty` | `string` | `array` | `object`
 ----------- | ------ | -------- | -------- | -------- | -------
@@ -1140,15 +1271,16 @@ matrix | false | ;color | ;color=blue | ;color=blue,black,brown | ;color=R,100,G
 matrix | true | ;color | ;color=blue | ;color=blue;color=black;color=brown | ;R=100;G=200;B=150
 label | false | . | .blue | .blue.black.brown | .R.100.G.200.B.150
 label | true | . | .blue | .blue.black.brown | .R=100.G=200.B=150
-simple | false | n/a | blue | blue,black,brown | R,100,G,200,B,150
-simple | true | n/a | blue | blue,black,brown | R=100,G=200,B=150
-form | false | color= | color=blue | color=blue,black,brown | color=R,100,G,200,B,150
-form | true | color= | color=blue | color=blue&color=black&color=brown | R=100&G=200&B=150
-spaceDelimited | false | n/a | n/a | color=blue%20black%20brown | color=R%20100%20G%20200%20B%20150
-pipeDelimited | false | n/a | n/a | color=blue\|black\|brown | color=R\|100\|G\|200\|B\|150
-deepObject | true | n/a | n/a | n/a | color[R]=100&color[G]=200&color[B]=150
-
-This object MAY be extended with [Specification Extensions](#specificationExtensions).
+simple | false | _empty_ | blue | blue,black,brown | R,100,G,200,B,150
+simple | true | _empty_ | blue | blue,black,brown | R=100,G=200,B=150
+form | false | <span style="white-space: nowrap;">?color=</span> | <span style="white-space: nowrap;">?color=blue</span> | <span style="white-space: nowrap;">?color=blue,black,brown</span> | <span style="white-space: nowrap;">?color=R,100,G,200,B,150</span>
+form | true | <span style="white-space: nowrap;">?color=</span> | <span style="white-space: nowrap;">?color=blue</span> | <span style="white-space: nowrap;">?color=blue&color=black&color=brown</span> | <span style="white-space: nowrap;">?R=100&G=200&B=150</span>
+spaceDelimited</span> | false | _n/a_ | _n/a_ | <span style="white-space: nowrap;">?color=blue%20black%20brown</span> | <span style="white-space: nowrap;">?color=R%20100%20G%20200%20B%20150</span>
+spaceDelimited | true | _n/a_ | _n/a_ | _n/a_ | _n/a_
+pipeDelimited | false | _n/a_ | _n/a_ | <span style="white-space: nowrap;">?color=blue%7Cblack%7Cbrown</span> | <span style="white-space: nowrap;">?color=R%7C100%7CG%7C200%7CB%7C150</span>
+pipeDelimited | true | _n/a_ | _n/a_ | _n/a_ | _n/a_
+deepObject | false | _n/a_ | _n/a_ | _n/a_ | _n/a_
+deepObject | true | _n/a_ | _n/a_ | _n/a_ | <span style="white-space: nowrap;">?color%5BR%5D=100&color%5BG%5D=200&color%5BB%5D=150</span>
 
 ##### Parameter Object Examples
 
@@ -1323,7 +1455,7 @@ This object MAY be extended with [Specification Extensions](#specificationExtens
 
 ##### Request Body Examples
 
-A request body with a referenced model definition.
+A request body with a referenced schema definition.
 ```json
 {
   "description": "user to add to the system",
@@ -1399,46 +1531,20 @@ content:
         externalValue: https://foo.bar/examples/user-example.whatever
 ```
 
-A body parameter that is an array of string values:
-```json
-{
-  "description": "user to add to the system",
-  "required": true,
-  "content": {
-    "text/plain": {
-      "schema": {
-        "type": "array",
-        "items": {
-          "type": "string"
-        }
-      }
-    }
-  }
-}
-```
-
-```yaml
-description: user to add to the system
-required: true
-content:
-  text/plain:
-    schema:
-      type: array
-      items:
-        type: string
-```
-
-
 #### <a name="mediaTypeObject"></a>Media Type Object
 Each Media Type Object provides schema and examples for the media type identified by its key.
 
+When `example` or `examples` are provided, the example SHOULD match the specified schema and be in the correct format as specified by the media type and its encoding.
+The `example` and `examples` fields are mutually exclusive, and if either is present it SHALL _override_ any `example` in the schema.
+See [Working With Examples](#working-with-examples) for further guidance regarding the different ways of specifying examples, including non-JSON/YAML values.
+
 ##### Fixed Fields
 Field Name | Type | Description
 ---|:---:|---
-<a name="mediaTypeSchema"></a>schema | [Schema Object](#schemaObject) | The schema defining the content of the request, response, or parameter.
-<a name="mediaTypeExample"></a>example | Any | Example of the media type.  The example object SHOULD be in the correct format as specified by the media type.  The `example` field is mutually exclusive of the `examples` field.  Furthermore, if referencing a `schema` which contains an example, the `example` value SHALL _override_ the example provided by the schema.
-<a name="mediaTypeExamples"></a>examples | Map[ `string`, [Example Object](#exampleObject) \| [Reference Object](#referenceObject)] | Examples of the media type.  Each example object SHOULD  match the media type and specified schema if present.  The `examples` field is mutually exclusive of the `example` field.  Furthermore, if referencing a `schema` which contains an example, the `examples` value SHALL _override_ the example provided by the schema.
-<a name="mediaTypeEncoding"></a>encoding | Map[`string`, [Encoding Object](#encodingObject)] | A map between a property name and its encoding information. The key, being the property name, MUST exist in the schema as a property. The encoding attribute SHALL only apply to [Request Body Objects](#requestBodyObject), and only when the media type is `multipart` or `application/x-www-form-urlencoded`.  If no Encoding Object is provided for a property, the behavior is determined by the default values documented for the Encoding Object.
+<a name="mediaTypeSchema"></a>schema | [Schema Object](#schemaObject) | The schema defining the content of the request, response, parameter, or header.
+<a name="mediaTypeExample"></a>example | Any | Example of the media type; see [Working With Examples](#working-with-examples).
+<a name="mediaTypeExamples"></a>examples | Map[ `string`, [Example Object](#exampleObject) \| [Reference Object](#referenceObject)] | Examples of the media type; see [Working With Examples](#working-with-examples).
+<a name="mediaTypeEncoding"></a>encoding | Map[`string`, [Encoding Object](#encodingObject)] | A map between a property name and information providing more control over the serialization of the value. The key, being the property name, MUST exist in the schema as a property. The encoding attribute SHALL only apply to [Request Body Objects](#requestBodyObject), and only when the media type is `multipart` or `application/x-www-form-urlencoded`.  If no Encoding Object is provided for a property, the behavior is determined by the default values documented for the Encoding Object.
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
 
@@ -1547,26 +1653,77 @@ requestBody:
     image/png: {}
 ```
 
-To upload multiple files, a `multipart` media type MUST be used:
+To upload multiple files, a `multipart` media type MUST be used as shown under [Example: Multipart Form with Multiple Files](#example-multipart-form-with-multiple-files).
 
-```yaml
-requestBody:
-  content:
-    multipart/form-data:
-      schema:
-        properties:
-          # The property name 'file' will be used for all files.
-          file:
-            type: array
-            items: {}
-```
+##### Support for x-www-form-urlencoded Request Bodies
 
-As seen in the section on `multipart/form-data` below, the empty schema for `items` indicates a media type of `application/octet-stream`.
+See [Encoding the `x-www-form-urlencoded` Media Type](#encoding-the-x-www-form-urlencoded-media-type) for guidance and examples, both with and without the `encoding` attribute.
 
-##### Support for x-www-form-urlencoded Request Bodies
+##### Special Considerations for `multipart` Content
+
+See [Encoding `multipart` Media Types](#encoding-multipart-media-types) for further guidance and examples, both with and without the `encoding` attribute.
+
+#### <a name="encodingObject"></a>Encoding Object
 
-To submit content using form url encoding via [RFC1866](https://tools.ietf.org/html/rfc1866), the following
-definition may be used:
+A single encoding definition applied to a single schema property.
+See [Appendix B](#dataTypeConversion) for a discussion of converting values of various types to string representations.
+
+Properties are correlated with `multipart` parts using the `name` parameter to `Content-Disposition: form-data`, and with `application/x-www-form-urlencoded` using the query string parameter names.
+In both cases, their order is implementation-defined.
+
+See [Appendix E](#percentEncodingAndFormMediaTypes) for a detailed examination of percent-encoding concerns for form media types.
+
+##### Fixed Fields
+
+###### Common Fixed Fields
+
+These fields MAY be used either with or without the RFC6570-style serialization fields defined in the next section below.
+
+Field Name | Type | Description
+---|:---:|---
+<a name="encodingContentType"></a>contentType | `string` | The `Content-Type` for encoding a specific property. The value is a comma-separated list, each element of which is either a specific media type (e.g. `image/png`) or a wildcard media type (e.g. `image/*`). Default value depends on the property type as shown in the table below.
+<a name="encodingHeaders"></a>headers | Map[`string`, [Header Object](#headerObject) \| [Reference Object](#referenceObject)] | A map allowing additional information to be provided as headers. `Content-Type` is described separately and SHALL be ignored in this section. This property SHALL be ignored if the request body media type is not a `multipart`.
+
+This object MAY be extended with [Specification Extensions](#specificationExtensions).
+
+The default values for `contentType` are as follows, where an _n/a_ in the `contentEncoding` column means that the presence or value of `contentEncoding` is irrelevant:
+
+Property `type` | Property `contentEncoding` | Default `contentType`
+--------------- | -------------------------- | ---------------------
+[_absent_](#binaryData) | _n/a_ | `application/octet-stream`
+`string` | _present_ | `application/octet-stream`
+`string` | _absent_ | `text/plain`
+`number`, `integer`, or `boolean` | _n/a_ | `text/plain`
+`object` | _n/a_ | `application/json`
+`array` | _n/a_ | according to the `type` of the `items` schema
+
+Determining how to handle a `type` value of `null` depends on how `null` values are being serialized.
+If `null` values are entirely omitted, then the `contentType` is irrelevant.
+See [Appendix B](#dataTypeConversion) for a discussion of data type conversion options.
+
+###### Fixed Fields for RFC6570-style Serialization
+
+Field Name | Type | Description
+---|:---:|---
+<a name="encodingStyle"></a>style | `string` | Describes how a specific property value will be serialized depending on its type.  See [Parameter Object](#parameterObject) for details on the [`style`](#parameterStyle) property. The behavior follows the same values as `query` parameters, including default values. Note that the initial `?` used in query strings is not used in `application/x-www-form-urlencoded` message bodies, and MUST be removed (if using an RFC6570 implementation) or simply not added (if constructing the string manually). This property SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encodingContentType) (implicit or explicit) SHALL be ignored.
+<a name="encodingExplode"></a>explode | `boolean` | When this is true, property values of type `array` or `object` generate separate parameters for each value of the array, or key-value-pair of the map.  For other types of properties this property has no effect. When [`style`](#encodingStyle) is `form`, the default value is `true`. For all other styles, the default value is `false`. Note that despite `false` being the default for `deepObject`, the combination of `false` with `deepObject` is undefined. This property SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encodingContentType) (implicit or explicit) SHALL be ignored.
+<a name="encodingAllowReserved"></a>allowReserved | `boolean` | When this is true, parameter values are serialized  using reserved expansion, as defined by [RFC6570](https://datatracker.ietf.org/doc/html/rfc6570#autoid-20), which allows [RFC3986's reserved character set](https://datatracker.ietf.org/doc/html/rfc3986#autoid-13), as well as percent-encoded triples, to pass through unchanged, while still percent-encoding all other disallowed characters (including `%` outside of percent-encoded triples). Applications are still responsible for percent-encoding reserved characters that are [not allowed in the query string](https://datatracker.ietf.org/doc/html/rfc3986#autoid-24) (`[`, `]`, `#`), or have a special meaning in `application/x-www-form-urlencoded` (`-`, `&`, `+`); see Appendices [C](#usingRFC6570Implementations) and [E](#percentEncodingAndFormMediaTypes) for details. The default value is `false`. This property SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encodingContentType) (implicit or explicit) SHALL be ignored.
+
+See also [Appendix C: Using RFC6570 Implementations](#usingRFC6570Implementations) for additional guidance, including on difficulties caused by the interaction between RFC6570's percent-encoding rules and the `multipart/form-data` media type.
+
+Note that the presence of at least one of `style`, `explode`, or `allowReserved` with an explicit value is equivalent to using `schema` with `in: query` Parameter Objects.
+The absence of all three of those fields is the equivalent of using `content`, but with the media type specified in `contentType` rather than through a Media Type Object.
+
+##### Encoding the `x-www-form-urlencoded` Media Type
+
+To submit content using form url encoding via [RFC1866](https://tools.ietf.org/html/rfc1866), use the `application/x-www-form-urlencoded` media type in the [Media Type Object](#mediaTypeObject) under the [Request Body Object](#requestBodyObject).
+This configuration means that the request body MUST be encoded per [RFC1866](https://tools.ietf.org/html/rfc1866) when passed to the server, after any complex objects have been serialized to a string representation.
+
+See [Appendix E](#percentEncodingAndFormMediaTypes) for a detailed examination of percent-encoding concerns for form media types.
+
+###### Example: URL Encoded Form with JSON Values
+
+When there is no [`encoding` field](#mediaTypeEncoding), the serialization strategy is based on the Encoding Object's default values:
 
 ```yaml
 requestBody:
@@ -1584,27 +1741,92 @@ requestBody:
             properties: {}
 ```
 
-In this example, the contents in the `requestBody` MUST be stringified per [RFC1866](https://tools.ietf.org/html/rfc1866/) when passed to the server.  In addition, the `address` field complex object will be stringified.
+With this example, consider an `id` of `f81d4fae-7dec-11d0-a765-00a0c91e6bf6` and a US-style address (with ZIP+4) as follows:
 
-When passing complex objects in the `application/x-www-form-urlencoded` content type, the default serialization strategy of such properties is described in the [`Encoding Object`](#encodingObject)'s [`style`](#encodingStyle) property as `form`.
+```json
+{
+  "streetAddress": "123 Example Dr.",
+  "city": "Somewhere",
+  "state": "CA",
+  "zip": "99999+1234"
+}
+```
 
-##### Special Considerations for `multipart` Content
+Assuming the most compact representation of the JSON value (with unnecessary whitespace removed), we would expect to see the following request body, where space characters have been replaced with `+` and `+`, `"`, `{`, and `}` have been percent-encoded to `%2B`, `%22`, `%7B`, and `%7D`, respectively:
 
-It is common to use `multipart/form-data` as a `Content-Type` when transferring request bodies to operations.  In contrast to 2.0, a `schema` is REQUIRED to define the input parameters to the operation when using `multipart` content.  This supports complex structures as well as supporting mechanisms for multiple file uploads.
+```urlencoded
+id=f81d4fae-7dec-11d0-a765-00a0c91e6bf6&address=%7B%22streetAddress%22:%22123+Example+Dr.%22,%22city%22:%22Somewhere%22,%22state%22:%22CA%22,%22zip%22:%2299999%2B1234%22%7D
+```
 
-In a `multipart/form-data` request body, each schema property, or each element of a schema array property, takes a section in the payload with an internal header as defined by [RFC7578](https://tools.ietf.org/html/rfc7578). The serialization strategy for each property of a `multipart/form-data` request body can be specified in an associated [`Encoding Object`](#encodingObject).
+Note that the `id` keyword is treated as `text/plain` per the [Encoding Object](#encodingObject)'s default behavior, and is serialized as-is.
+If it were treated as `application/json`, then the serialized value would be a JSON string including quotation marks, which would be percent-encoded as `%22`.
 
-When passing in `multipart` types, boundaries MAY be used to separate sections of the content being transferred – thus, the following default `Content-Type`s are defined for `multipart`:
+Here is the `id` parameter (without `address`) serialized as `application/json` instead of `text/plain`, and then encoded per RFC1866:
 
-* If the property is a primitive, or an array of primitive values, the default Content-Type is `text/plain`
-* If the property is complex, or an array of complex values, the default Content-Type is `application/json`
-* If the property is a `type: string` with a `contentEncoding`, the default Content-Type is `application/octet-stream`
+```urlencoded
+id=%22f81d4fae-7dec-11d0-a765-00a0c91e6bf6%22
+```
 
-Per the JSON Schema specification, `contentMediaType` without `contentEncoding` present is treated as if `contentEncoding: identity` were present.  While useful for embedding text documents such as `text/html` into JSON strings, it is not useful for a `multipart/form-data` part, as it just causes the document to be treated as `text/plain` instead of its actual media type.  Use the Encoding Object without `contentMediaType` if no `contentEncoding` is required.
+###### Example: URL Encoded Form with Binary Values
 
-Note that only `multipart/*` media types with named parts can be described as shown here.  Note also that while `multipart/form-data` originally defined a per-part `Content-Transfer-Encoding` header that could indicate base64 encoding (`contentEncoding: base64`), it has been deprecated for use with HTTP as of [RFC7578](https://www.rfc-editor.org/rfc/rfc7578#section-4.7).
+Note that `application/x-www-form-urlencoded` is a text format, which requires base64-encoding any binary data:
 
-Examples:
+```YAML
+requestBody:
+  content:
+    application/x-www-form-urlencoded:
+      schema:
+        type: object
+        properties:
+          name:
+            type: string
+          icon:
+            # The default with "contentEncoding" is application/octet-stream,
+            # so we need to set image media type(s) in the Encoding Object.
+            type: string
+            contentEncoding: base64url
+  encoding:
+    icon:
+      contentType: image/png, image/jpeg
+```
+
+Given a name of `example` and a solid red 2x2-pixel PNG for `icon`, this
+would produce a request body of:
+
+```urlencoded
+name=example&icon=iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAIAAAD91JpzAAAABGdBTUEAALGPC_xhBQAAADhlWElmTU0AKgAAAAgAAYdpAAQAAAABAAAAGgAAAAAAAqACAAQAAAABAAAAAqADAAQAAAABAAAAAgAAAADO0J6QAAAAEElEQVQIHWP8zwACTGCSAQANHQEDqtPptQAAAABJRU5ErkJggg%3D%3D
+```
+
+Note that the `=` padding characters at the end need to be percent-encoded, even with the "URL safe" `contentEncoding: base64url`.
+Some base64-decoding implementations may be able to use the string without the padding per [RFC4648 §3.2](https://datatracker.ietf.org/doc/html/rfc4648#section-3.2).
+However, this is not guaranteed, so it may be more interoperable to keep the padding and rely on percent-decoding.
+
+##### Encoding `multipart` Media Types
+
+It is common to use `multipart/form-data` as a `Content-Type` when transferring forms as request bodies.  In contrast to 2.0, a `schema` is REQUIRED to define the input parameters to the operation when using `multipart` content.  This supports complex structures as well as supporting mechanisms for multiple file uploads.
+
+The `form-data` disposition and its `name` parameter are mandatory for `multipart/form-data` ([RFC7578 §4.2](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.2)).
+Array properties are handled by applying the same `name` to multiple parts, as is recommended by [RFC7578 §4.3](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.3) for supplying multiple values per form field.
+See [RFC7578 §5](https://www.rfc-editor.org/rfc/rfc7578.html#section-5) for guidance regarding non-ASCII part names.
+
+Various other `multipart` types, most notable `multipart/mixed` ([RFC2046 §5.1.3](https://www.rfc-editor.org/rfc/rfc2046.html#section-5.1.3)) neither require nor forbid specific `Content-Disposition` values, which means care must be taken to ensure that any values used are supported by all relevant software.
+It is not currently possible to correlate schema properties with unnamed, ordered parts in media types such as `multipart/mixed`, but implementations MAY choose to support such types when `Content-Disposition: form-data` is used with a `name` parameter.
+
+Note that there are significant restrictions on what headers can be used with `multipart` media types in general ([RFC2046 §5.1](https://www.rfc-editor.org/rfc/rfc2046.html#section-5.1)) and `multi-part/form-data` in particular ([RFC7578 §4.8](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.8)).
+
+Note also that `Content-Transfer-Encoding` is deprecated for `multipart/form-data` ([RFC7578 §4.7](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.7)) where binary data is supported, as it is in HTTP.
+
++Using `contentEncoding` for a multipart field is equivalent to specifying an [Encoding Object](#encodingObject) with a `headers` field containing `Content-Transfer-Encoding` with a schema that requires the value used in `contentEncoding`.
++If `contentEncoding` is used for a multipart field that has an Encoding Object with a `headers` field containing `Content-Transfer-Encoding` with a schema that disallows the value from `contentEncoding`, the result is undefined for serialization and parsing.
+
+Note that as stated in [Working with Binary Data](#binaryData), if the Encoding Object's `contentType`, whether set explicitly or implicitly through its default value rules, disagrees with the `contentMediaType` in a Schema Object, the `contentMediaType` SHALL be ignored.
+Because of this, and because the Encoding Object's `contentType` defaulting rules do not take the Schema Object's` contentMediaType` into account, the use of `contentMediaType` with an Encoding Object is NOT RECOMMENDED.
+
+See [Appendix E](#percentEncodingAndFormMediaTypes) for a detailed examination of percent-encoding concerns for form media types.
+
+###### Example: Basic Multipart Form
+
+When the `encoding` attribute is _not_ used, the encoding is determined by the Encoding Object's defaults:
 
 ```yaml
 requestBody:
@@ -1614,50 +1836,26 @@ requestBody:
         type: object
         properties:
           id:
+            # default for primitives without a special format is text/plain
             type: string
             format: uuid
-          address:
-            # default Content-Type for objects is `application/json`
-            type: object
-            properties: {}
           profileImage:
-            # Content-Type for application-level encoded resource is `text/plain`
+            # default for string with binary format is `application/octet-stream`
             type: string
-            contentMediaType: image/png
-            contentEncoding: base64
-          children:
-            # default Content-Type for arrays is based on the _inner_ type (`text/plain` here)
-            type: array
-            items:
-              type: string
+            format: binary
           addresses:
-            # default Content-Type for arrays is based on the _inner_ type (object shown, so `application/json` in this example)
+            # default for arrays is based on the type in the `items`
+            # subschema, which is an object, so `application/json`
             type: array
             items:
               type: object
               $ref: '#/components/schemas/Address'
 ```
 
-An `encoding` attribute is introduced to give you control over the serialization of parts of `multipart` request bodies.  This attribute is _only_ applicable to request bodies, and _only_ for `multipart` and `application/x-www-form-urlencoded` media types.
-
-#### <a name="encodingObject"></a>Encoding Object
-
-A single encoding definition applied to a single schema property.
-
-##### Fixed Fields
-Field Name | Type | Description
----|:---:|---
-<a name="encodingContentType"></a>contentType | `string` | The Content-Type for encoding a specific property. Default value depends on the property type: for `object` - `application/json`;  for `array` – the default is defined based on the inner type; for all other cases the default is `application/octet-stream`. The value can be a specific media type (e.g. `application/json`), a wildcard media type (e.g. `image/*`), or a comma-separated list of the two types. 
-<a name="encodingHeaders"></a>headers | Map[`string`, [Header Object](#headerObject) \| [Reference Object](#referenceObject)] | A map allowing additional information to be provided as headers, for example `Content-Disposition`.  `Content-Type` is described separately and SHALL be ignored in this section. This property SHALL be ignored if the request body media type is not a `multipart`.
-<a name="encodingStyle"></a>style | `string` | Describes how a specific property value will be serialized depending on its type.  See [Parameter Object](#parameterObject) for details on the [`style`](#parameterStyle) property. The behavior follows the same values as `query` parameters, including default values. This property SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encodingContentType) (implicit or explicit) SHALL be ignored.
-<a name="encodingExplode"></a>explode | `boolean` | When this is true, property values of type `array` or `object` generate separate parameters for each value of the array, or key-value-pair of the map.  For other types of properties this property has no effect. When [`style`](#encodingStyle) is `form`, the default value is `true`. For all other styles, the default value is `false`. This property SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encodingContentType) (implicit or explicit) SHALL be ignored.
-<a name="encodingAllowReserved"></a>allowReserved | `boolean` | Determines whether the parameter value SHOULD allow reserved characters, as defined by [RFC3986](https://tools.ietf.org/html/rfc3986#section-2.2) `:/?#[]@!$&'()*+,;=` to be included without percent-encoding. The default value is `false`. This property SHALL be ignored if the request body media type is not `application/x-www-form-urlencoded` or `multipart/form-data`. If a value is explicitly defined, then the value of [`contentType`](#encodingContentType) (implicit or explicit) SHALL be ignored.
-
-This object MAY be extended with [Specification Extensions](#specificationExtensions).
-
-##### Encoding Object Example
+###### Example: Multipart Form with Encoding Objects
 
-`multipart/form-data` allows for binary parts:
+Using `encoding`, we can set more specific types for binary data, or non-JSON formats for complex values.
+We can also describe headers for each part:
 
 ```yaml
 requestBody:
@@ -1667,25 +1865,30 @@ requestBody:
         type: object
         properties:
           id:
-            # default is text/plain
+            # default is `text/plain`
             type: string
             format: uuid
-          address:
-            # default is application/json
-            type: object
-            properties: {}
-          historyMetadata:
-            # need to declare XML format!
-            description: metadata in XML format
-            type: object
-            properties: {}
-          profileImage: {}
+          addresses:
+            # default based on the `items` subschema would be
+            # `application/json`, but we want these address objects
+            # serialized as `application/xml` instead
+            description: addresses in XML format
+            type: array
+            items:
+                $ref: '#/components/schemas/Address'
+          profileImage:
+            # default is application/octet-stream, but we can declare
+            # a more specific image type or types
+            type: string
+            format: binary
       encoding:
-        historyMetadata:
+        addresses:
           # require XML Content-Type in utf-8 encoding
+          # This is applied to each address part corresponding
+          # to each address in he array
           contentType: application/xml; charset=utf-8
         profileImage:
-          # only accept png/jpeg
+          # only accept png or jpeg
           contentType: image/png, image/jpeg
           headers:
             X-Rate-Limit-Limit:
@@ -1694,27 +1897,24 @@ requestBody:
                 type: integer
 ```
 
-`application/x-www-form-urlencoded` is a text format, which requires base64-encoding any binary data:
+###### Example: Multipart Form with Multiple Files
 
-```YAML
+In accordance with [RFC7578 §4.3](https://www.rfc-editor.org/rfc/rfc7578.html#section-4.3), multiple files for a single form field are uploaded using the same name (`file` in this example) for each file's part:
+
+```yaml
 requestBody:
   content:
-    application/x-www-form-urlencoded:
+    multipart/form-data:
       schema:
-        type: object
         properties:
-          name:
-            type: string
-          icon:
-            # default for type string is text/plain, need to declare
-            # the appropriate contentType in the Encoding Object
-            type: string
-            contentEncoding: base64url
-  encoding:
-    icon:
-      contentType: image/png, image/jpeg
+          # The property name 'file' will be used for all files.
+          file:
+            type: array
+            items: {}
 ```
 
+As seen in the [Encoding Object's `contentType` field documentation](#encodingContentType), the empty schema for `items` indicates a media type of `application/octet-stream`.
+
 #### <a name="responsesObject"></a>Responses Object
 
 A container for the expected responses of an operation.
@@ -1983,7 +2183,7 @@ $response.header.Location | https://example.org/subscription/1
 
 ##### Callback Object Examples
 
-The following example uses the user provided `queryUrl` query string parameter to define the callback URL.  This is an example of how to use a callback object to describe a WebHook callback that goes with the subscription operation to enable registering for the WebHook.
+The following example uses the user provided `queryUrl` query string parameter to define the callback URL.  This is similar to a [webhook](#oasWebhooks), but differs in that the callback only occurs because of the initial request that sent the `queryUrl`.
 
 ```yaml
 myCallback:
@@ -2019,19 +2219,43 @@ transactionCallback:
 
 #### <a name="exampleObject"></a>Example Object
 
+An object grouping an internal or external example value with basic `summary` and `description` metadata.
+This object is typically used in properties named `examples` (plural), and is a [referenceable](#referenceObject) alternative to older `example` (singular) fields that do not support referencing or metadata.
+
+Examples allow demonstration of the usage of properties, parameters and objects within OpenAPI.
+
 ##### Fixed Fields
 Field Name | Type | Description
 ---|:---:|---
 <a name="exampleSummary"></a>summary | `string` | Short description for the example.
 <a name="exampleDescription"></a>description | `string` | Long description for the example. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
 <a name="exampleValue"></a>value | Any | Embedded literal example. The `value` field and `externalValue` field are mutually exclusive. To represent examples of media types that cannot naturally represented in JSON or YAML, use a string value to contain the example, escaping where necessary.
-<a name="exampleExternalValue"></a>externalValue | `string` | A URI that points to the literal example. This provides the capability to reference examples that cannot easily be included in JSON or YAML documents.  The `value` field and `externalValue` field are mutually exclusive. See the rules for resolving [Relative References](#relativeReferencesURI).
+<a name="exampleExternalValue"></a>externalValue | `string` | A URI that identifies the literal example. This provides the capability to reference examples that cannot easily be included in JSON or YAML documents.  The `value` field and `externalValue` field are mutually exclusive. See the rules for resolving [Relative References](#relativeReferencesURI).
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
 
-In all cases, the example value is expected to be compatible with the type schema 
-of its associated value.  Tooling implementations MAY choose to 
-validate compatibility automatically, and reject the example value(s) if incompatible.
+In all cases, the example value SHOULD be compatible with the schema of its associated value.
+Tooling implementations MAY choose to validate compatibility automatically, and reject the example value(s) if incompatible.
+
+#### Working With Examples
+
+Example Objects can be used in both [Parameter Objects](#parameterObject) and [Media Type Objects](#mediaTypeObject).
+In both Objects, this is done through the `examples` (plural) field.
+However, there are several other ways to provide examples:  The `example` (singular) field that is mutually exclusive with `examples` in both Objects, and two keywords (the deprecated singular `example` and the current plural `examples`, which takes an array of examples) in the [Schema Object](#schemaObject) that appears in the `schema` field of both Objects.
+Each of these fields has slightly different considerations.
+
+The Schema Object's fields are used to show example values without regard to how they might be formatted as parameters or within media type representations.
+The `examples` array is part of JSON Schema and is the preferred way to include examples in the Schema Object, while `example` is retained purely for compatibility with older versions of the OpenAPI Specification.
+
+The mutually exclusive fields in the Parameter or Media Type Objects are used to show example values which SHOULD both match the schema and be formatted as they would appear as a serialized parameter or within a media type representation.
+The exact serialization and encoding is determined by various fields in the Parameter Object, or in the Media Type Object's [Encoding Object](#encodingObject).
+Because examples using these fields represent the final serialized form of the data, they SHALL _override_ any `example` in the corresponding Schema Object.
+
+The singular `example` field in the Parameter or Media Type object is concise and convenient for simple examples, but does not offer any other advantages over using Example Objects under `examples`.
+
+Some examples cannot be represented directly in JSON or YAML.
+For all three ways of providing examples, these can be shown as string values with any escaping necessary to make the string valid in the JSON or YAML format of the OpenAPI Description document.
+With the Example Object, such values can alternatively be handled through the `externalValue` field.
 
 ##### Example Object Examples
 
@@ -2091,44 +2315,118 @@ responses:
             $ref: '#/components/examples/confirmation-success'
 ```
 
+Two different uses of JSON strings:
 
-#### <a name="linkObject"></a>Link Object
-
-The `Link object` represents a possible design-time link for a response.
-The presence of a link does not guarantee the caller's ability to successfully invoke it, rather it provides a known relationship and traversal mechanism between responses and other operations.
-
-Unlike _dynamic_ links (i.e. links provided **in** the response payload), the OAS linking mechanism does not require link information in the runtime response.
-
-For computing links, and providing instructions to execute them, a [runtime expression](#runtimeExpression) is used for accessing values in an operation and using them as parameters while invoking the linked operation.  
-
-##### Fixed Fields
-
-Field Name  |  Type  | Description
----|:---:|---
-<a name="linkOperationRef"></a>operationRef | `string` | A relative or absolute URI reference to an OAS operation. This field is mutually exclusive of the `operationId` field, and MUST point to an [Operation Object](#operationObject). Relative `operationRef` values MAY be used to locate an existing [Operation Object](#operationObject) in the OpenAPI definition. See the rules for resolving [Relative References](#relativeReferencesURI).
-<a name="linkOperationId"></a>operationId  | `string` | The name of an _existing_, resolvable OAS operation, as defined with a unique `operationId`.  This field is mutually exclusive of the `operationRef` field.  
-<a name="linkParameters"></a>parameters   | Map[`string`, Any \| [{expression}](#runtimeExpression)] | A map representing parameters to pass to an operation as specified with `operationId` or identified via `operationRef`. The key is the parameter name to be used (optionally qualified with the parameter location, e.g. `path.id` for an `id` parameter in the path), whereas the value can be a constant or an expression to be evaluated and passed to the linked operation.
-<a name="linkRequestBody"></a>requestBody | Any \| [{expression}](#runtimeExpression) | A literal value or [{expression}](#runtimeExpression) to use as a request body when calling the target operation.
-<a name="linkDescription"></a>description  | `string` | A description of the link. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
-<a name="linkServer"></a>server       | [Server Object](#serverObject) | A server object to be used by the target operation.
+First, a request or response body that is just a JSON string (not an object containing a string):
 
-This object MAY be extended with [Specification Extensions](#specificationExtensions).
+```json
+"application/json": {
+  "schema": {
+    "type": "string"
+  },
+  "examples": {
+    "jsonBody": {
+      "description": "A body of just the JSON string \"json\"",
+      "value": "json"
+    }
+  }
+}
+```
 
-A linked operation MUST be identified using either an `operationRef` or `operationId`.
-In the case of an `operationId`, it MUST be unique and resolved in the scope of the OAS document.
-Because of the potential for name clashes, the `operationRef` syntax is preferred 
-for OpenAPI documents with external references.
+```yaml
+application/json:
+  schema:
+    type: string
+  examples:
+    jsonBody:
+      description: 'A body of just the JSON string "json"'
+      value: json
+```
 
-Note that it is not possible to provide a constant value to `parameters` that matches the syntax of a runtime expression.
-It is possible to have ambiguous parameter names, e.g. `name: id, in: path` and `name: path.id, in: query`; this is NOT RECOMMENDED and the behavior is implementation-defined, however implementations SHOULD prefer the qualified interpretation (`path.id` as a path parameter), as the names can always be qualified to disambiguate them (e.g. using `query.path.id` for the query paramter).
+In the above example, we can just show the JSON string (or any JSON value) as-is, rather than stuffing a serialized JSON value into a JSON string, which would have looked like `"\"json\""`.
 
-##### Examples
 
-Computing a link from a request operation where the `$request.path.id` is used to pass a request parameter to the linked operation.
+In contrast, a JSON string encoded inside of a URL-style form body:
 
-```yaml
-paths:
-  /users/{id}:
+```json
+"application/x-www-form-urlencoded": {
+  "schema": {
+    "type": "object",
+    "properties": {
+      "jsonValue": {
+        "type": "string"
+      }
+    }
+  },
+  "encoding": {
+    "jsonValue": {
+      "contentType": "application/json"
+    }
+  },
+  "examples": {
+    "jsonFormValue": {
+      "description": "The JSON string \"json\" as a form value",
+      "value": "jsonValue=%22json%22"
+    }
+  }
+}
+```
+
+```yaml
+application/x-www-form-urlencoded:
+  schema:
+    type: object
+    properties:
+      jsonValue:
+        type: string
+  encoding:
+    jsonValue:
+      contentType: application/json
+  examples:
+    jsonFormValue:
+      description: 'The JSON string "json" as a form value'
+      value: jsonValue=%22json%22
+```
+
+In this example, the JSON string had to be serialized before encoding it into the URL form value, so the example includes the quotation marks that are part of the JSON serialization, which are then URL percent-encoded.
+
+#### <a name="linkObject"></a>Link Object
+
+The `Link object` represents a possible design-time link for a response.
+The presence of a link does not guarantee the caller's ability to successfully invoke it, rather it provides a known relationship and traversal mechanism between responses and other operations.
+
+Unlike _dynamic_ links (i.e. links provided **in** the response payload), the OAS linking mechanism does not require link information in the runtime response.
+
+For computing links, and providing instructions to execute them, a [runtime expression](#runtimeExpression) is used for accessing values in an operation and using them as parameters while invoking the linked operation.  
+
+##### Fixed Fields
+
+Field Name  |  Type  | Description
+---|:---:|---
+<a name="linkOperationRef"></a>operationRef | `string` | A URI identifying an OAS operation. This field is mutually exclusive of the `operationId` field, and MUST point to an [Operation Object](#operationObject). Relative `operationRef` values MAY be used to locate an existing [Operation Object](#operationObject) in the OpenAPI description. See the rules for resolving [Relative References](#relativeReferencesURI).
+<a name="linkOperationId"></a>operationId  | `string` | The name of an _existing_, resolvable OAS operation, as defined with a unique `operationId`.  This field is mutually exclusive of the `operationRef` field.  
+<a name="linkParameters"></a>parameters   | Map[`string`, Any \| [{expression}](#runtimeExpression)] | A map representing parameters to pass to an operation as specified with `operationId` or identified via `operationRef`. The key is the parameter name to be used (optionally qualified with the parameter location, e.g. `path.id` for an `id` parameter in the path), whereas the value can be a constant or an expression to be evaluated and passed to the linked operation.
+<a name="linkRequestBody"></a>requestBody | Any \| [{expression}](#runtimeExpression) | A literal value or [{expression}](#runtimeExpression) to use as a request body when calling the target operation.
+<a name="linkDescription"></a>description  | `string` | A description of the link. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
+<a name="linkServer"></a>server       | [Server Object](#serverObject) | A server object to be used by the target operation.
+
+This object MAY be extended with [Specification Extensions](#specificationExtensions).
+
+A linked operation MUST be identified using either an `operationRef` or `operationId`.
+In the case of an `operationId`, it MUST be unique and resolved in the scope of the OpenAPI description.
+Because of the potential for name clashes, the `operationRef` syntax is preferred 
+for multi-document OpenAPI descriptions.
+
+Note that it is not possible to provide a constant value to `parameters` that matches the syntax of a runtime expression.
+It is possible to have ambiguous parameter names, e.g. `name: id, in: path` and `name: path.id, in: query`; this is NOT RECOMMENDED and the behavior is implementation-defined, however implementations SHOULD prefer the qualified interpretation (`path.id` as a path parameter), as the names can always be qualified to disambiguate them (e.g. using `query.path.id` for the query parameter).
+
+##### Examples
+
+Computing a link from a request operation where the `$request.path.id` is used to pass a request parameter to the linked operation.
+
+```yaml
+paths:
+  /users/{id}:
     parameters:
     - name: id
       in: path
@@ -2268,18 +2566,63 @@ Expressions can be embedded into string values by surrounding the expression wit
 
 #### <a name="headerObject"></a>Header Object
 
-The Header Object follows the structure of the [Parameter Object](#parameterObject) with the following changes:
+Describes a single header for [HTTP responses](#responseHeaders) and for [individual parts in `multipart` representations](#encodingHeaders); see the relevant [Response Object](#responseObject) and [Encoding Object](#encodingObject) documentation for restrictions on which headers can be described.
+
+The Header Object follows the structure of the [Parameter Object](#parameterObject), including determining its serialization strategy based on whether `schema` or `content` is present,  with the following changes:
 
 1. `name` MUST NOT be specified, it is given in the corresponding `headers` map.
 1. `in` MUST NOT be specified, it is implicitly in `header`.
-1. All traits that are affected by the location MUST be applicable to a location of `header` (for example, [`style`](#parameterStyle)).
+1. All traits that are affected by the location MUST be applicable to a location of `header` (for example, [`style`](#parameterStyle)).  This means that `allowEmptyValue` and `allowReserved` MUST NOT be used, and `style`, if used, MUST be limited to `simple`.
+
+##### Fixed Fields
+
+###### Common Fixed Fields
+
+These fields MAY be used with either `content` or `schema`.
+
+Field Name | Type | Description
+---|:---:|---
+<a name="headerDescription"></a>description | `string` | A brief description of the header. This could contain examples of use. [CommonMark syntax](https://spec.commonmark.org/) MAY be used for rich text representation.
+<a name="headerRequired"></a>required | `boolean` | Determines whether this header is mandatory. The default value is `false`.
+<a name="headerDeprecated"></a> deprecated | `boolean` | Specifies that the header is deprecated and SHOULD be transitioned out of usage. Default value is `false`.
+
+This object MAY be extended with [Specification Extensions](#specificationExtensions).
+
+###### Fixed Fields for use with `schema`
+
+For simpler scenarios, a [`schema`](#headerSchema) and [`style`](#headerStyle) can describe the structure and syntax of the header.
+When `example` or `examples` are provided in conjunction with the `schema` object, the example MUST follow the prescribed serialization strategy for the header.
+
+Serializing with `schema` is NOT RECOMMENDED for headers with parameters (name=value pairs following a `;`) in their values, or where values might have non-URL-safe characters; see [Appendix D](#serializingHeadersAndCookies) for details.
+
+When `example` or `examples` are provided in conjunction with the `schema` object, the example SHOULD match the specified schema and follow the prescribed serialization strategy for the header.
+The `example` and `examples` fields are mutually exclusive, and if either is present it SHALL _override_ any `example` in the schema.
+
+Field Name | Type | Description
+---|:---:|---
+<a name="headerStyle"></a>style | `string` | Describes how the header value will be serialized.  The default (and only legal value for headers) is `simple`.
+<a name="headerExplode"></a>explode | `boolean` | When this is true, header values of type `array` or `object` generate a single header whose value is a comma-separated list of the array items or key-value pairs of the map, see [Style Examples](#style-examples). For other data types this property has no effect. The default value is `false`.
+<a name="headerSchema"></a>schema | [Schema Object](#schemaObject) \| [Reference Object](#referenceObject) | The schema defining the type used for the header.
+<a name="headerExample"></a>example | Any | Example of the header's potential value; see [Working With Examples](#working-with-examples).
+<a name="headerExamples"></a>examples | Map[ `string`, [Example Object](#exampleObject) \| [Reference Object](#referenceObject)] | Examples of the header's potential value; see [Working With Examples](#working-with-examples).
+
+See also [Appendix C: Using RFC6570 Implementations](#usingRFC6570Implementations) for additional guidance.
+
+###### Fixed Fields for use with `content`
+
+For more complex scenarios, the [`content`](#headerContent) property can define the media type and schema of the header, as well as give examples of its use.
+Using `content` with a `text/plain` media type is RECOMMENDED for headers where the `schema` strategy is not appropriate.
+
+Field Name | Type | Description
+---|:---:|---
+<a name="headerContent"></a>content | Map[`string`, [Media Type Object](#mediaTypeObject)] | A map containing the representations for the header. The key is the media type and the value describes it. The map MUST only contain one entry.
 
 ##### Header Object Example
 
 A simple header of type `integer`:
 
 ```json
-{
+"X-Rate-Limit-Limit": {
   "description": "The number of allowed requests in the current period",
   "schema": {
     "type": "integer"
@@ -2288,9 +2631,36 @@ A simple header of type `integer`:
 ```
 
 ```yaml
-description: The number of allowed requests in the current period
-schema:
-  type: integer
+X-Rate-Limit-Limit:
+  description: The number of allowed requests in the current period
+  schema:
+    type: integer
+```
+
+Requiring that a strong `ETag` header (with a value starting with `"` rather than `W/`) is present.  Note the use of `content`, because using `schema` and `style` would require the `"` to be percent-encoded as `%22`:
+
+```json
+"ETag": {
+  "required": true,
+  "content": {
+    "text/plain": {
+      "schema": {
+        "type": "string",
+        "pattern": "^\""
+      }
+    }
+  }
+}
+```
+
+```yaml
+ETag:
+  required: true
+  content:
+    text/plain:
+      schema:
+        type: string
+        pattern: ^" 
 ```
 
 #### <a name="tagObject"></a>Tag Object
@@ -2326,7 +2696,7 @@ description: Pets operations
 
 A simple object to allow referencing other components in the OpenAPI document, internally and externally.
 
-The `$ref` string value contains a URI [RFC3986](https://tools.ietf.org/html/rfc3986), which identifies the location of the value being referenced.
+The `$ref` string value contains a URI [RFC3986](https://tools.ietf.org/html/rfc3986), which identifies the value being referenced.
 
 See the rules for resolving [Relative References](#relativeReferencesURI).
 
@@ -2382,7 +2752,7 @@ These types can be objects, but also primitives and arrays. This object is a sup
 
 For more information about the properties, see [JSON Schema Core](https://tools.ietf.org/html/draft-bhutton-json-schema-00) and [JSON Schema Validation](https://tools.ietf.org/html/draft-bhutton-json-schema-validation-00).
 
-Unless stated otherwise, the property definitions follow those of JSON Schema and do not add any additional semantics.
+Unless stated otherwise, the property definitions follow those of JSON Schema and do not add any additional semantics; this includes keywords such as `$schema`, `$id`, `$ref`, and `$dynamicRef` being URIs rather than URLs.
 Where JSON Schema indicates that behavior is defined by the application (e.g. for annotations), OAS also defers the definition of semantics to the application consuming the OpenAPI document.
 
 ##### Properties
@@ -2398,7 +2768,8 @@ The following properties are taken from the JSON Schema specification but their
 
 In addition to the JSON Schema properties comprising the OAS dialect, the Schema Object supports keywords from any other vocabularies, or entirely arbitrary properties.
 
-The OpenAPI Specification's base vocabulary is comprised of the following keywords:
+JSON Schema implementations MAY choose to treat keywords defined by the OpenAPI Specification's base vocabulary as [unknown keywords](https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#section-4.3.1), due to its inclusion in the OAS dialect with a [`$vocabulary`](https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#section-8.1.2) value of `false`.
+The OAS base vocabulary is comprised of the following keywords:
 
 ##### <a name="baseVocabulary"></a>Fixed Fields
 
@@ -2443,11 +2814,12 @@ The [XML Object](#xmlObject) contains additional information about the available
 
 It is important for tooling to be able to determine which dialect or meta-schema any given resource wishes to be processed with: JSON Schema Core, JSON Schema Validation, OpenAPI Schema dialect, or some custom meta-schema.
 
-The `$schema` keyword MAY be present in any root Schema Object, and if present MUST be used to determine which dialect should be used when processing the schema. This allows use of Schema Objects which comply with other drafts of JSON Schema than the default Draft 2020-12 support. Tooling MUST support the <a href="#dialectSchemaId">OAS dialect schema id</a>, and MAY support additional values of `$schema`.
+The `$schema` keyword MAY be present in any Schema Object that is a [schema resource root](https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-00#section-4.3.5), and if present MUST be used to determine which dialect should be used when processing the schema. This allows use of Schema Objects which comply with other drafts of JSON Schema than the default Draft 2020-12 support. Tooling MUST support the <a href="#dialectSchemaId">OAS dialect schema id</a>, and MAY support additional values of `$schema`.
 
-To allow use of a different default `$schema` value for all Schema Objects contained within an OAS document, a `jsonSchemaDialect` value may be set within the <a href="#oasObject">OpenAPI Object</a>. If this default is not set, then the OAS dialect schema id MUST be used for these Schema Objects. The value of `$schema` within a Schema Object always overrides any default.
+To allow use of a different default `$schema` value for all Schema Objects contained within an OAS document, a `jsonSchemaDialect` value may be set within the <a href="#oasObject">OpenAPI Object</a>. If this default is not set, then the OAS dialect schema id MUST be used for these Schema Objects. The value of `$schema` within a resource root Schema Object always overrides any default.
 
-When a Schema Object is referenced from an external resource which is not an OAS document (e.g. a bare JSON Schema resource), then the value of the `$schema` keyword for schemas within that resource MUST follow [JSON Schema rules](https://tools.ietf.org/html/draft-bhutton-json-schema-00#section-8.1.1).
+For standalone JSON Schema documents that do not set `$schema`, or for Schema Objects in OpenAPI description documents that are _not_ [complete documents](#documentStructure), the dialect SHOULD be assumed to be the OAS dialect.
+However, for maximum interoperability, it is RECOMMENDED that OpenAPI description authors explicitly set the dialect through `$schema` in such documents.
 
 ##### Schema Object Examples
 
@@ -2557,10 +2929,12 @@ additionalProperties:
   "required": [
     "name"
   ],
-  "example": {
-    "name": "Puma",
-    "id": 1
-  }
+  "examples": [
+    {
+      "name": "Puma",
+      "id": 1
+    }
+  ]
 }
 ```
 
@@ -2574,8 +2948,8 @@ properties:
     type: string
 required:
 - name
-example:
-  name: Puma
+examples:
+- name: Puma
   id: 1
 ```
 
@@ -2896,6 +3270,8 @@ When request bodies or response payloads may be one of a number of different sch
 This hint can be used to aid in serialization, deserialization, and validation.
 The Discriminator Object does this by implicitly or explicitly associating the possible values of a named property with alternative schemas.
 
+Note that `discriminator` MUST NOT change the validation outcome of the schema.
+
 ##### Fixed Fields
 Field Name | Type | Description
 ---|:---:|---
@@ -2906,9 +3282,14 @@ This object MAY be extended with [Specification Extensions](#specificationExtens
 
 ##### Conditions for Using the Discriminator Object
 The Discriminator Object is legal only when using one of the composite keywords `oneOf`, `anyOf`, `allOf`.
+
 In both the `oneOf` and `anyOf` use cases, where those keywords are adjacent to `discriminator`, all possible schemas MUST be listed explicitly.
+
 To avoid redundancy, the discriminator MAY be added to a parent schema definition, and all schemas building on the parent schema via an `allOf` construct may be used as an alternate schema.
 
+The `allOf` form of `discriminator` is _only_ useful for non-validation use cases; validation with the parent schema with this form of `discriminator` _does not_ perform a search for child schemas or use them in validation in any way.
+This is because `discriminator` cannot change the validation outcome, and no standard JSON Schema keyword connects the parent schema to the child schemas.
+
 The behavior of any configuration of `oneOf`, `anyOf`, `allOf` and `discriminator` that is not described above is undefined.
 
 ##### Options for Mapping Values to Schemas
@@ -2948,7 +3329,7 @@ MyResponseType:
     propertyName: petType
 ```
 
-The expectation now is that a property with name `petType` _MUST_ be present in the response payload, and the value will correspond to the name of a schema defined in the OAS document.  Thus the response payload:
+The expectation now is that a property with name `petType` _MUST_ be present in the response payload, and the value will correspond to the name of a schema defined in the OpenAPI description.  Thus the response payload:
 
 ```json
 {
@@ -3053,16 +3434,23 @@ See examples for expected behavior.
 Field Name | Type | Description
 ---|:---:|---
 <a name="xmlName"></a>name | `string` | Replaces the name of the element/attribute used for the described schema property. When defined within `items`, it will affect the name of the individual XML elements within the list. When defined alongside `type` being `array` (outside the `items`), it will affect the wrapping element and only if `wrapped` is `true`. If `wrapped` is `false`, it will be ignored.
-<a name="xmlNamespace"></a>namespace | `string` | The URI of the namespace definition. This MUST be in the form of an absolute URI.
+<a name="xmlNamespace"></a>namespace | `string` | The URI of the namespace definition. Value MUST be in the form of a non-relative URI.
 <a name="xmlPrefix"></a>prefix | `string` | The prefix to be used for the [name](#xmlName).
 <a name="xmlAttribute"></a>attribute | `boolean` | Declares whether the property definition translates to an attribute instead of an element. Default value is `false`.
 <a name="xmlWrapped"></a>wrapped | `boolean` | MAY be used only for an array definition. Signifies whether the array is wrapped (for example, `<books><book/><book/></books>`) or unwrapped (`<book/><book/>`). Default value is `false`. The definition takes effect only when defined alongside `type` being `array` (outside the `items`).
 
 This object MAY be extended with [Specification Extensions](#specificationExtensions).
 
+The `namespace` keyword is intended to match the syntax of [XML namespaces](https://www.w3.org/TR/xml-names11/), although there are a few caveats:
+
+* Versions 3.1.0, 3.0.3, and earlier of this specification erroneously used the term "absolute URI" instead of "non-relative URI", so authors using namespaces that include a fragment should check tooling support carefully.
+* XML allows but discourages relative URI-references, while this specification outright forbids them.
+* XML 1.1 allows IRIs ([RFC3987](https://datatracker.ietf.org/doc/html/rfc3987)) as namespaces, and specifies that namespaces are compared without any encoding or decoding, which means that IRIs encoded to meet this specification's URI syntax requirement cannot be compared to IRIs as-is.
+
 ##### XML Object Examples
 
-The examples of the XML object definitions are included inside a property definition of a [Schema Object](#schemaObject) with a sample of the XML representation of it.
+Each of the following examples represent the value of the `properties` keyword in a [Schema Object](#schemaObject) that is omitted for brevity.
+The JSON and YAML representations of the `properties` value are followed by an example XML representation produced for the single property shown.
 
 ###### No XML Element
 
@@ -3650,6 +4038,102 @@ security:
     - read:pets
 ```
 
+###### Security Requirement in a Referenced Document
+
+See [Resolving Implicit Connections](#resolvingImplicitConnections) for more information.
+
+First, our entry document is where parsing begins. It defines the `MySecurity` security scheme to be JWT-based, and it defines a Path Item as a reference to a component in another document:
+
+```HTTP
+GET /api/description/openapi HTTP/1.1
+Host: www.example.com
+Accept: application/openapi+json
+```
+
+```json
+"components": {
+  "securitySchemes": {
+    "MySecurity": {
+      "type": "http",
+      "scheme": "bearer",
+      "bearerFormat": "JWT"
+    }
+  }
+},
+"paths": {
+  "/foo": {
+    "$ref": "other#/components/pathItems/Foo"
+  }
+}
+```
+
+```HTTP
+GET /api/description/openapi HTTP/1.1
+Host: www.example.com
+Accept: application/openapi+yaml
+```
+
+```yaml
+components:
+  securitySchemes:
+    MySecurity:
+      type: http
+      scheme: bearer
+      bearerFormat: JWT
+paths:
+  /foo:
+    $ref: "other#/components/pathItems/Foo"
+```
+
+Next, we have our referenced document, `other`. The fact that we don't use file extensions gives the client the flexibility to choose an acceptable format on a resource-by-resource basis, assuming both representations are available:
+
+```HTTP
+GET /api/description/other HTTP/1.1
+Host: www.example.com
+Accept: application/openapi+json
+```
+
+```json
+"components": {
+  "securitySchemes": {
+    "MySecurity": {
+      "type": "http",
+      "scheme": "basic"
+    }
+  },
+  "pathItems": {
+    "Foo": {
+      "get": {
+        "security": [
+          "MySecurity": []
+        ]
+      }
+    }
+  }
+}
+```
+
+```HTTP
+GET /api/description/other HTTP/1.1
+Host: www.example.com
+Accept: application/openapi+yaml
+```
+
+```yaml
+components:
+  securitySchemes:
+    MySecurity:
+      type: http
+      scheme: basic
+  pathItems:
+    Foo:
+      get:
+        security:
+        - MySecurity: []
+```
+
+In the `other` document, the referenced path item has a Security Requirement for a Security Scheme, `MySecurity`. The same Security Scheme exists in the original entry document. As outlined in [Resolving Implicit Connections](#resolvingImplicitConnections), `MySecurity` is resolved with an [implementation-defined behavior](#undefinedAndImplementationDefinedBehavior). However, documented in that section, it is RECOMMENDED that tools resolve component names from the [entry document](#documentStructure). As with all implementation-defined behavior, it is important to check tool documentation to determine which behavior is supported.
+
 ### <a name="specificationExtensions"></a>Specification Extensions
 
 While the OpenAPI Specification tries to accommodate most use cases, additional data can be added to extend the specification at certain points.
@@ -3658,9 +4142,14 @@ The extensions properties are implemented as patterned fields that are always pr
 
 Field Pattern | Type | Description
 ---|:---:|---
-<a name="infoExtensions"></a>^x- | Any | Allows extensions to the OpenAPI Schema. The field name MUST begin with `x-`, for example, `x-internal-id`. Field names beginning `x-oai-` and `x-oas-` are reserved for uses defined by the [OpenAPI Initiative](https://www.openapis.org/). The value can be `null`, a primitive, an array or an object.
+<a name="extensionProperties"></a>^x- | Any | Allows extensions to the OpenAPI Schema. The field name MUST begin with `x-`, for example, `x-internal-id`. Field names beginning `x-oai-` and `x-oas-` are reserved for uses defined by the [OpenAPI Initiative](https://www.openapis.org/). The value can be any valid JSON value (`null`, a primitive, an array or an object.)
 
-The extensions may or may not be supported by the available tooling, but those may be extended as well to add requested support (if tools are internal or open-sourced).
+The OpenAPI Initiative maintains several [extension registries](https://spec.openapis.org/registry/index.html), including registries for [individual extension keywords](https://spec.openapis.org/registry/extension/) and [extension keyword namespaces](https://spec.openapis.org/registry/namespace/).
+
+Extensions are one of the best ways to prove the viability of proposed additions to the specification.  
+It is therefore RECOMMENDED that implementations be designed for extensibility to support community experimentation.
+
+Support for any one extension is OPTIONAL, and support for one extension does not imply support for others.
 
 ### <a name="securityFiltering"></a>Security Filtering
 
@@ -3674,6 +4163,31 @@ Two examples of this:
 1. The [Paths Object](#pathsObject) MAY be present but empty. It may be counterintuitive, but this may tell the viewer that they got to the right place, but can't access any documentation. They would still have access to at least the [Info Object](#infoObject) which may contain additional information regarding authentication.
 2. The [Path Item Object](#pathItemObject) MAY be empty. In this case, the viewer will be aware that the path exists, but will not be able to see any of its operations or parameters. This is different from hiding the path itself from the [Paths Object](#pathsObject), because the user will be aware of its existence. This allows the documentation provider to finely control what the viewer can see.
 
+## Security Considerations
+
+### OpenAPI Document Formats
+
+OpenAPI description documents use JSON, YAML, and JSON Schema, and therefore share their security considerations:
+- [JSON](https://www.iana.org/assignments/media-types/application/json)
+- [YAML](https://www.iana.org/assignments/media-types/application/yaml)
+- [JSON Schema Core](https://json-schema.org/draft/2020-12/json-schema-core#section-13)
+- [JSON Schema Validation](https://json-schema.org/draft/2020-12/json-schema-validation#name-security-considerations)
+
+### Tooling and Usage Scenarios
+
+In addition, OpenAPI description documents are processed by a wide variety of tooling for numerous different purposes, such as client code generation, documentation generation, server side routing, and API testing. OpenAPI description authors must consider the risks of the scenarios where the OpenAPI description may be used.
+
+### Security Schemes
+
+An OpenAPI description describes the security schemes used to protect the resources it defines. The security schemes available offer varying degrees of protection. Factors such as the sensitivity of the data and the potential impact of a security breach should guide the selection of security schemes for the API resources. Some security schemes, such as basic auth and OAuth Implicit flow, are supported for compatibility with existing APIs. However, their inclusion in OpenAPI does not constitute an endorsement of their use, particularly for highly sensitive data or operations.
+
+### Handling External Resources
+
+OpenAPI description documents may contain references to external resources that may be dereferenced automatically by consuming tools. External resources may be hosted on different domains that may be untrusted. References in an OpenAPI document, or across OpenAPI documents within a multi-document OpenAPI description, may cause a cycle. Tooling must detect and handle cycles to prevent resource exhaustion.
+
+### Markdown and HTML Sanitization
+
+Certain properties allow the use of Markdown which can contain HTML including script. It is the responsibility of tooling to appropriately sanitize the Markdown.
 
 ## <a name="revisionHistory"></a>Appendix A: Revision History
 
@@ -3694,3 +4208,385 @@ Version   | Date       | Notes
 1.2       | 2014-03-14 | Initial release of the formal document.
 1.1       | 2012-08-22 | Release of Swagger 1.1
 1.0       | 2011-08-10 | First release of the Swagger Specification
+
+## <a name="dataTypeConversion"></a>Appendix B: Data Type Conversion
+
+Serializing typed data to plain text, which can occur in `text/plain` message bodies or `multipart` parts, as well as in the `application/x-www-form-urlencoded` format in either URL query strings or message bodies, involves significant implementation- or application-defined behavior.
+
+Schema Objects validate data based on the [JSON Schema data model](https://datatracker.ietf.org/doc/html/draft-wright-json-schema-00#section-4.2), which only recognizes four primitive data types: strings (which are [only broadly interoperable as UTF-8](https://datatracker.ietf.org/doc/html/rfc7159#section-8.1)), numbers, booleans, and `null`.
+Notably, integers are not a distinct type from other numbers, with `type: integer` being a convenience defined mathematically, rather than based on the presence or absence of a decimal point in any string representation.
+
+The [Parameter Object](#parameterObject), [Header Object](#headerObject) and [Encoding Object](#encodingObject) offer features to control how to arrange values from array or object types.
+They can also be used to control how strings are further encoded to avoid reserved or illegal characters.
+However, there is no general-purpose specification for converting schema-validated non-UTF-8 primitive data types (or entire arrays or objects) to strings.
+
+Two cases do offer standards-based guidance:
+
+* [RFC3987 §3.1](https://datatracker.ietf.org/doc/html/rfc3987#section-3.1) provides guidance for converting non-Unicode strings to UTF-8, particularly in the context of URIs (and by extension, the form media types which use the same encoding rules)
+* [RFC6570 §2.3](https://www.rfc-editor.org/rfc/rfc6570#section-2.3) specifies which values, including but not limited to `null`, are considered _undefined_ and therefore treated specially in the expansion process when serializing based on that specification
+
+Implementations of RFC6570 often have their own conventions for converting non-string values, but these are implementation-specific and not defined by the RFC itself.
+This is one reason for the OpenAPI Specification to leave these conversions as implementation-defined:  It allows using RFC6570 implementations regardless of how they choose to perform the conversions.
+
+To control the serialization of numbers, booleans, and `null` (or other values RFC6570 deems to be undefined) more precisely, schemas can be defined as `type: string` and constrained using `pattern`, `enum`, `format`, and other keywords to communicate how applications must pre-convert their data prior to schema validation.
+The resulting strings would not require any further type conversion.
+
+The `format` keyword can assist in serialization.
+Some formats (such as `date-time`) are unambiguous, while others (such as [`decimal`](https://spec.openapis.org/registry/format/decimal.html) in the [Format Registry](https://spec.openapis.org/registry/format/)) are less clear.
+However, care must be taken with `format` to ensure that the specific formats are supported by all relevant tools as unrecognized formats are ignored.
+
+Requiring input as pre-formatted, schema-validated strings also improves round-trip interoperability as not all programming languages and environments support the same data types.
+
+## <a name="usingRFC6570Implementations"></a>Appendix C: Using RFC6570 Implementations
+
+Serialization is defined in terms of RFC6570 URI Templates in two scenarios:
+
+Object | Condition
+------ | ---------
+[Parameter Object](#parameterObject) | When `schema` is present
+[Encoding Object](#encodingObject) | When encoding for `application/x-www-form-urlencoded` and any of `style`, `explode`, or `allowReserved` are used
+
+Implementations of this specification MAY use an implementation of RFC6570 to perform variable expansion, however, some caveats apply.
+
+Note that when using `style: form` RFC6570 expansion to produce an `application/x-www-form-urlencoded` HTTP message body, it is necessary to remove the `?` prefix that is produced to satisfy the URI query string syntax.
+
+When using `style` and similar keywords to produce a `multipart/form-data` body, the query string names are placed in the `name` parameter to the `Content-Disposition` part header, and the values are placed in the corresponding part body; the `?`, `=`, and `&` characters are not used.
+Note that while [RFC7578](https://datatracker.ietf.org/doc/html/rfc7578) allows using RFC3986 percent-encoding in "file names", it does not otherwise address the use of percent-encoding within the format.
+RFC7578 discusses character set and encoding issues for `multipart/form-data` in detail, and it is RECOMMENDED that OpenAPI Description authors read this guidance carefully before deciding to use RFC6570-based serialization with this media type.
+
+Note also that not all RFC6570 implementations support all four levels of operators, all of which are needed to fully support the OpenAPI Specification's usage.
+Using an implementation with a lower level of support will require additional manual construction of URI Templates to work around the limitations.
+
+### Equivalences Between Fields and RFC6570 Operators
+
+Certain field values translate to RFC6570 operators (or lack thereof):
+
+field | value | equivalent
+----- | ----- | ----------
+style | simple | _n/a_
+style | matrix | `;` prefix operator
+style | label | `.` prefix operator
+style | form | `?` prefix operator
+allowReserved | `false` | _n/a_
+allowReserved | `true` | `+` prefix operator
+explode | `false` | _n/a_
+explode | `true` | `*` modifier suffix
+
+Multiple `style: form` parameters are equivalent to a single RFC6570 [variable list](https://www.rfc-editor.org/rfc/rfc6570#section-2.2) using the `?` prefix operator:
+
+```YAML
+parameters:
+- name: foo
+  in: query
+  schema:
+    type: object
+  explode: true
+- name: bar
+  in: query
+  schema:
+    type: string
+```
+
+This example is equivalent to RFC6570's `{?foo*,bar}`, and ***NOT*** `{?foo*}{&bar}`, which is problematic because if `foo` is not defined, the result will be an invalid URI.
+The `&` prefix operator has no equivalent in the Parameter Object.
+
+Note that RFC6570 does not specify behavior for compound values beyond the single level addressed by `explode`.  The results of using objects or arrays where no behavior is clearly specified for them is implementation-defined.
+
+### Non-RFC6570 Field Values and Combinations
+
+Configurations with no direct RFC6570 equivalent SHOULD also be handled according to RFC6570.
+Implementations MAY create a properly delimited URI Template with variables for individual names and values using RFC6570 regular or reserved expansion (based on `allowReserved`).
+
+This includes:
+  * the styles `pipeDelimited`, `spaceDelimited`, and `deepObject`, which have no equivalents at all
+  * the combination of the style `form` with `allowReserved: true`, which is not allowed because only one prefix operator can be used at a time
+  * any parameter name that is not a legal RFC6570 variable name
+
+The Parameter Object's `name` field has a much more permissive syntax than [RFC6570 variable name syntax](https://www.rfc-editor.org/rfc/rfc6570#section-2.3).
+A parameter name that includes characters outside of the allowed RFC6570 variable character set MUST be percent-encoded before it can be used in a URI Template.
+
+### Examples
+
+Let's say we want to use the following data in a form query string, where `formulas` is exploded, and `words` is not:
+
+```YAML
+formulas:
+  a: x+y
+  b: x/y
+  c: x^y
+words:
+- math
+- is
+- fun
+```
+
+#### RFC6570-Equivalent Expansion
+
+This array of parameter objects uses regular `style: form` expansion, fully supported by RFC6570:
+
+```YAML
+parameters:
+- name: formulas
+  in: query
+  schema:
+    type: object
+    additionalProperties:
+      type: string
+  explode: true
+- name: words
+  in: query
+  schema:
+    type: array
+    items:
+      type: string
+```
+
+This translates to the following URI Template:
+
+```urlencoded
+{?formulas*,words}
+```
+
+when expanded with the data given earlier, we get:
+
+```urlencoded
+?a=x%2By&b=x%2Fy&c=x%5Ey&words=math,is,fun
+```
+
+#### Expansion With Non-RFC6570-Supported Options
+
+But now let's say that (for some reason), we really want that `/` in the `b` formula to show up as-is in the query string, and we want our words to be space-separated like in a written phrase.
+To do that, we'll add `allowReserved: true` to `formulas`, and change to `style: spaceDelimited` for `words`:
+
+```YAML
+parameters:
+- name: formulas
+  in: query
+  schema:
+    type: object
+    additionalProperties:
+      type: string
+  explode: true
+  allowReserved: true
+- name: words
+  in: query
+  style: spaceDelimited
+  schema:
+    type: array
+    items:
+      type: string
+```
+
+We can't combine the `?` and `+` RFC6570 prefixes, and there's no way with RFC6570 to replace the `,` separator with a space character.
+So we need to restructure the data to fit a manually constructed URI Template that passes all of the pieces through the right sort of expansion.
+
+Here is one such template, using a made-up convention of `words.0` for the first entry in the words value, `words.1` for the second, and `words.2` for the third:
+
+```urlencoded
+?a={+a}&b={+b}&c={+c}&words={words.0} {words.1} {words.2}
+```
+
+RFC6570 [mentions](https://www.rfc-editor.org/rfc/rfc6570.html#section-2.4.2) the use of `.` "to indicate name hierarchy in substructures," but does not define any specific naming convention or behavior for it.
+Since the `.` usage is not automatic, we'll need to construct an appropriate input structure for this new template.
+
+We'll also need to pre-process the values for `formulas` because while `/` and most other reserved characters are allowed in the query string by RFC3986, `[`, `]`, and `#` [are not](https://datatracker.ietf.org/doc/html/rfc3986#appendix-A), and `&`, `=`, and `+` all have [special behavior](https://www.rfc-editor.org/rfc/rfc1866#section-8.2.1) in the `application/x-www-form-urlencoded` format, which is what we are using in the query string.
+
+Setting `allowReserved: true` does _not_ make reserved characters that are not allowed in URIs allowed, it just allows them to be _passed through expansion unchanged._
+Therefore, any tooling still needs to percent-encode those characters because reserved expansion will not do it, but it _will_ leave the percent-encoded triples unchanged.
+See also [Appendix E](#percentEncodingAndFormMediaTypes) for further guidance on percent-encoding and form media types, including guidance on handling the delimiter characters for `spaceDelimited`, `pipeDelimited`, and `deepObject` in parameter names and values.
+
+So here is our data structure that arranges the names and values to suit the template above, where values for `formulas` have `[]#&=+` pre-percent encoded (although only `+` appears in this example):
+
+```YAML
+a: x%2By
+b: x/y
+c: x^y
+words.0: math
+words.1: is
+words.2: fun
+```
+
+Expanding our manually assembled template with our restructured data yields the following query string:
+
+```urlencoded
+?a=x%2By&b=x/y&c=x%5Ey&words=math%20is%20fun
+```
+The `/` and the pre-percent-encoded `%2B` have been left alone, but the disallowed `^` character (inside a value) and space characters (in the template but outside of the expanded variables) were percent-encoded.
+
+#### Undefined Values and Manual URI Template Construction
+
+Care must be taken when manually constructing templates to handle the values that [RFC6570 considers to be _undefined_](https://datatracker.ietf.org/doc/html/rfc6570#section-2.3) correctly:
+
+```YAML
+formulas: {}
+words:
+- hello
+- world
+```
+
+Using this data with our original RFC6570-friendly URI Template, `{?formulas*,words}`, produces the following:
+
+
+```urlencoded
+?words=hello,world
+```
+
+This means that the manually constructed URI Template and restructured data need to leave out the `formulas` object entirely so that the `words` parameter is the first and only parameter in the query string.
+
+Restructured data:
+
+```YAML
+words.0: hello
+words.1: world
+```
+
+Manually constructed URI Template:
+
+```urlencoded
+?words={words.0} {words.1}
+```
+
+Result:
+
+```urlencoded
+?words=hello%20world
+```
+
+#### Illegal Variable Names as Parameter Names
+In this example, the heart emoji is not legal in URI Template names (or URIs):
+
+```YAML
+parameters:
+- name: ❤️
+  in: query
+  schema:
+    type: string
+```
+
+We can't just pass `❤️: love!` to an RFC6570 implementation.
+Instead, we have to pre-percent-encode the name (which is a six-octet UTF-8 sequence) in both the data and the URI Template:
+
+```YAML
+"%E2%9D%A4%EF%B8%8F": love!
+```
+
+```urlencoded
+{?%E2%9D%A4%EF%B8%8F}
+```
+
+This will expand to the result:
+
+```urlencoded
+?%E2%9D%A4%EF%B8%8F=love%21
+```
+
+## <a name="serializingHeadersAndCookies"></a>Appendix D: Serializing Headers and Cookies
+
+RFC6570's percent-encoding behavior is not always appropriate for `in: header` and `in: cookie` parameters.
+In many cases, it is more appropriate to use `content` with a media type such as `text/plain` and require the application to assemble the correct string.
+
+For both cookies ([RFC6265](https://www.rfc-editor.org/rfc/rfc6265)) and HTTP headers using the structured fields ([RFC8941](https://www.rfc-editor.org/rfc/rfc8941)) syntax, non-ASCII content is handled using base64 encoding (`contentEncoding: base64`).
+Note that the standard base64 encoding alphabet includes non-URL-safe characters that are percent-encoded by RFC6570 expansion; serializing values through both encodings is NOT RECOMMENDED.
+While `contentEncoding` also supports the `base64url` encoding, which is URL-safe, the header and cookie RFCs do not mention this encoding.
+
+Most HTTP headers predate the structured field syntax, and a comprehensive assessment of their syntax and encoding rules is well beyond the scope of this specification.
+While [RFC8187](https://www.rfc-editor.org/rfc/rfc8187) recommends percent-encoding HTTP field (header or trailer) parameters, these parameters appear after a `;` character.
+With `style: simple`, that delimiter would itself be percent-encoded, violating the general HTTP field syntax.
+
+Using `style: form` with `in: cookie` is ambiguous for a single value, and incorrect for multiple values.
+This is true whether the multiple values are the result of using `explode: true` or not.
+
+This style is specified to be equivalent to RFC6570 form expansion which includes the `?` character (see Appendix C for more details), which is not part of the cookie syntax.
+However, examples of this style in past versions of this specification have not included the `?` prefix, suggesting that the comparison is not exact.
+Because implementations that rely on an RFC6570 implementation and those that perform custom serialization based on the style example will produce different results, it is implementation-defined as to which of the two results is correct.
+
+For multiple values, `style: form` is always incorrect as name=value pairs in cookies are delimited by `; ` (a semicolon followed by a space character) rather than `&`.
+
+## <a name="percentEncodingAndFormMediaTypes"></a>Appendix E: Percent-Encoding and Form Media Types
+
+_**NOTE:** In this section, the `application/x-www-form-urlencoded` and `multipart/form-data` media types are abbreviated as `form-urlencoded` and `form-data`, respectively, for readability._
+
+Percent-encoding is used in URIs and media types that derive their syntax from URIs.
+This process is concerned with three sets of characters, the names of which vary among specifications but are defined as follows for the purposes of this section:
+
+* _unreserved_ characters do not need to be percent-encoded; while it is safe to percent-encode them, doing so produces a URI that is [not normalized](https://datatracker.ietf.org/doc/html/rfc3986#section-6.2.2.2)
+* _reserved_ characters either have special behavior in the URI syntax (such as delimiting components) or are reserved for other specifications that need to define special behavior (e.g. `form-urlencoded` defines special behavior for `=`, `&`, and `+`)
+* _unsafe_ characters are known to cause problems when parsing URIs in certain environments
+
+Unless otherwise specified, this section uses RFC3986's definition of [reserved](https://datatracker.ietf.org/doc/html/rfc3986#section-2.2) and [unreserved](https://datatracker.ietf.org/doc/html/rfc3986#section-2.3), and defines the unsafe set as all characters not included in either of those sets.
+
+### Percent-Encoding and `form-urlencoded`
+
+Each URI component (such as the query string) considers some of the reserved characters to be unsafe, either because they serve as delimiters between the components (e.g. `#`), or (in the case of `[` and `]`) were historically considered globally unsafe but were later given reserved status for limited purposes.
+
+Reserved characters with no special meaning defined within a component can be left un-percent encoded.
+However, other specifications can define special meanings, requiring percent-encoding for those characters outside of the additional special meanings.
+
+The `form-urlencoded` media type defines special meanings for `=` and `&` as delimiters, and `+` as the replacement for the space character (instead of its percent-encoded form of `%20`).
+This means that while these three characters are reserved-but-allowed in query strings by RFC3986, they must be percent-encoded in `form-urlencoded` query strings except when used for their `form-urlencoded` purposes; see [Appendix C](#usingRFC6570Implementations) for an example of handling `+` in form values.
+
+### Percent-Encoding and `form-data`
+
+[RFC7578 §2](https://datatracker.ietf.org/doc/html/rfc7578#section-2) suggests RFC3986-based percent-encoding as a mechanism to keep text-based per-part header data such as file names within the ASCII character set.
+This suggestion was not part of older (pre-2015) specifications for `form-data`, so care must be taken to ensure interoperability.
+
+The `form-data` media type allows arbitrary text or binary data in its parts, so percent-encoding is not needed and is likely to cause interoperability problems unless the `Content-Type` of the part is defined to require it.
+
+### Generating and Validating URIs and `form-urlencoded` Strings
+
+URI percent encoding and the `form-urlencoded` media type have complex specification histories spanning multiple revisions and, in some cases, conflicting claims of ownership by different standards bodies.
+Unfortunately, these specifications each define slightly different percent-encoding rules, which need to be taken into account if the URIs or `form-urlencoded` message bodies will be subject to strict validation.
+(Note that many URI parsers do not perform validation by default.)
+
+This specification normatively cites the following relevant standards:
+
+Specification | Date | OAS Usage | Percent-Encoding | Notes
+------------- | ---- | --------- | ----- | -----
+[RFC3986 URI&nbsp;Generic&nbsp;Syntax](https://datatracker.ietf.org/doc/html/rfc3986) | 01/2005 | URI/URL syntax | RFC3986 | obsoletes RFC1738, RFC2396
+[RFC6570 URI&nbsp;Template](https://datatracker.ietf.org/doc/html/rfc6570) | 03/2012 | style-based serialization | RFC3986 | does not use `+` for <code>form&#8209;urlencoded</code>
+[RFC1866&nbsp;§8.2.1 form&#8209;urlencoded](https://datatracker.ietf.org/doc/html/rfc1866#section-8.2.1) | 11/1995 | content-based serialization | RFC1738 | obsoleted by [HTML&nbsp;4.01&nbsp;§17.13.4.1](https://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.1), [WHATWG&nbsp;URL&nbsp;§5](https://url.spec.whatwg.org/#urlencoded-serializing)
+
+Style-based serialization is used in the [Parameter Object](#parameterObject) when `schema` is present, and in the [Encoding Object](#encodingObject) when at least one of `style`, `explode`, or `allowReserved` is present.
+See [Appendix C](#usingRFC6570Implementations) for more details of RFC6570's two different approaches to percent-encoding, including an example involving `+`.
+
+Content-based serialization is defined by the [Media Type Object](#mediaTypeObject), and used with the [Parameter Object](#parameterObject) when the `content` field is present, and with the [Encoding Object](#encodingObject) based on the `contentType` field when the style fields listed in the previous section are absent.
+Each part is encoded based on the media type (e.g. `text/plain` or `application/json`), and must then be percent-encoded for use in a `form-urlencoded` string.
+
+Note that content-based serialization for `form-data` does not expect or require percent-encoding in the data, only in per-part header values.
+
+#### Interoperability with Historical Specifications
+
+In most cases, generating query strings in strict compliance with RFC3986 is sufficient to pass validation (including JSON Schema's `format: uri` and `format: uri-reference`), but some `form-urlencoded` implementations still expect the slightly more restrictive RFC1738 rules to be used.
+
+Since all RFC1738-compliant URIs are compliant with RFC3986, applications needing to ensure historical interoperability SHOULD use RFC1738's rules.
+
+#### Interoperability with Web Browser Environments
+
+WHATWG is a [web browser-oriented](https://whatwg.org/faq#what-is-the-whatwg-working-on) standards group that has defined a "URL Living Standard" for parsing and serializing URLs in a browser context, including parsing and serializing `form-urlencoded` data.
+WHATWG's percent-encoding rules for query strings are different depending on whether the query string is [being treated as `form-urlencoded`](https://url.spec.whatwg.org/#application-x-www-form-urlencoded-percent-encode-set) (where it requires more percent-encoding than RFC1738) or [as part of the generic syntax](https://url.spec.whatwg.org/#query-percent-encode-set), where it allows characters that RFC3986 forbids.
+
+Implementations needing maximum compatibility with web browsers SHOULD use WHATWG's `form-urlencoded` percent-encoding rules.
+However, they SHOULD NOT rely on WHATWG's less stringent generic query string rules, as the resulting URLs would fail RFC3986 validation, including JSON Schema's `format: uri` and `format: uri-reference`.
+
+### Decoding URIs and `form-urlencoded` Strings
+
+The percent-decoding algorithm does not care which characters were or were not percent-decoded, which means that URIs percent-encoded according to any specification will be decoded correctly.
+
+Similarly, all `form-urlencoded` decoding algorithms simply add `+`-for-space handling to the percent-decoding algorithm, and will work regardless of the encoding specification used.
+
+However, care must be taken to use `form-urlencoded` decoding if `+` represents a space, and to use regular percent-decoding if `+` represents itself as a literal value.
+
+### Percent-Encoding and Illegal or Reserved Delimiters
+
+The `[` and `]`, `|`, and space characters, which are used as delimiters for the `deepObject`, `pipeDelimited`, and `spaceDelimited` styles, respectively, all MUST be percent-encoded to comply with RFC3986.
+This requires users to pre-encode the character(s) in some other way in parameter names and values to distinguish them from the delimiter usage when using one of these styles.
+
+The space character is always illegal and encoded in some way by all implementations of all versions of the relevant standards.
+While one could use the `form-urlencoded` convention of `+` to distinguish spaces in parameter names and values from `spaceDelimited` delimiters encoded as `%20`, the specifications define the decoding as a single pass, making it impossible to distinguish the different usages in the decoded result.
+
+Some environments use `[`, `]`, and possibly `|` unencoded in query strings without apparent difficulties, and WHATWG's generic query string rules do not require percent-encoding them.
+Code that relies on leaving these delimiters unencoded, while using regular percent-encoding for them within names and values, is not guaranteed to be interoperable across all implementations.
+
+For maximum interoperability, it is RECOMMENDED to either define and document an additional escape convention while percent-encoding the delimiters for these styles, or to avoid these styles entirely.
+The exact method of additional encoding/escaping is left to the API designer, and is expected to be performed before serialization and encoding described in this specification, and reversed after this specification's encoding and serialization steps are reversed.
+This keeps it outside of the processes governed by this specification.