Clarify Link Obj parameters as best we can (3.0.4)

This acknowledges the ambiguity in the key and value syntax of the
Link Object's `parameter` field, and provides a bit of guidance
on how to implement it.  Sadly it is not possible to fully solve
in a point release.

Author: handrews

versions/3.0.4.md

@@ -2060,7 +2060,7 @@ 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.
 <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, whereas the value can be a constant or an expression to be evaluated and passed to the linked operation.  The parameter name can be qualified using the [parameter location](#parameterIn) `[{in}.]{name}` for operations that use the same parameter name in different locations (e.g. path\.id).
+<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, whereas the value can be a constant or an expression to be evaluated and passed to the linked operation (see further details below).
 <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.
@@ -2072,6 +2072,16 @@ In the case of an `operationId`, it MUST be unique and resolved in the scope of
 Because of the potential for name clashes, the `operationRef` syntax is preferred 
 for specifications with external references.
 
+Keys and values for `parameters` have multiple syntaxes:
+
+* The key can either be just the parameter name, or can be qualified using the [parameter location](#parameterIn) `[{in}.]{name}` for operations that use the same parameter name in different locations (e.g. path\.id).
+* The value can be a literal value or a [Runtime Expression](#runtimeExpression)
+
+Certain keys and values for `parameters` can be ambiguous, in which case their handling is implementation-defined as it was not spelled out in earlier versions of OAS 3.0.  However, it is RECOMMENDED that: 
+
+* Keys that match unqualified parameter names be treated as those names, as a parameter that is (confusingly) named to appear qualified (e.g. `path\.id`) can be qualified to disambiguate it (e.g. `path\.path\.id`)
+* Values that are valid runtime expressions be handled as runtime expressions, although this means that it is not possible to pass a literal value that looks like a runtime expression
+
 ##### Examples
 
 Computing a link from a request operation where the `$request.path.id` is used to pass a request parameter to the linked operation.