Correction: Clarify units and reference geodetic system for latitude and longitude (#138)

* Clarify units and reference geodetic system for latitude and longitude

Replaces "decimal degrees" with "a real number of degrees" for greater
clarity and specifically refers to the WGS84 coordinate system for
latitude and longitude the way it is for altitude.

Fixed #135 and #136.

* Clean up GeopositionCoordinates constructor steps as well

Author: reillyeon

index.html

@@ -1117,8 +1117,9 @@ <h4>
           `latitude`, `longitude`, and `accuracy` attributes
         </h4>
         <p>
-          The <dfn>latitude</dfn> and <dfn>longitude</dfn> attributes are
-          geographic coordinates specified in decimal degrees.
+          The <dfn>latitude</dfn> and <dfn>longitude</dfn> attributes denote
+          the position, specified as a real number of degrees, in the [[WGS84]]
+          coordinate system.
         </p>
         <p>
           The <dfn>accuracy</dfn> attribute denotes the accuracy level of the
@@ -1172,19 +1173,22 @@ <h2>
           {{GeolocationCoordinates}} instance:
             <ol>
               <li>Initialize |coord|'s {{GeolocationCoordinates/latitude}}
-              attribute to a geographic coordinate in decimal degrees.
+              attribute to a latitude, specified as a real number of degrees, in
+              the [[WGS84]] coordinate system.
               </li>
               <li>Initialize |coord|'s {{GeolocationCoordinates/longitude}}
-              attribute to a geographic coordinate in decimal degrees.
+              attribute to a longitude, specified as a real number of degrees,
+              in the [[WGS84]] coordinate system.
               </li>
               <li>Initialize |coord|'s {{GeolocationCoordinates/accuracy}}
               attribute to a non-negative real number. The value SHOULD
               correspond to a 95% confidence level with respect to the
               longitude and latitude values.
               </li>
               <li>Initialize |coord|'s {{GeolocationCoordinates/altitude}}
-              attribute in meters above the [[WGS84]] ellipsoid, or `null` if
-              the implementation cannot provide altitude information.
+              attribute to a height, in meters, above the [[WGS84]] ellipsoid,
+              or `null` if the implementation cannot provide altitude
+              information.
               </li>
               <li>Initialize |coord|'s
               {{GeolocationCoordinates/altitudeAccuracy}} attribute as
@@ -1194,15 +1198,16 @@ <h2>
               level.
               </li>
               <li>Initialize |coord|'s {{GeolocationCoordinates/speed}}
-              attribute to a non-negative real number, or as `null` if the
-              implementation cannot provide speed information.
+              attribute to a speed, as a non-negative real number of meters per
+              second, or as `null` if the implementation cannot provide speed
+              information.
               </li>
               <li>Initialize |coord|'s {{GeolocationCoordinates/heading}}
-              attribute in degrees, or `null` if the implementation cannot
-              provide heading information. If the hosting device is stationary
-              (i.e., the value of the {{GeolocationCoordinates/speed}}
-              attribute is 0), then initialize the
-              {{GeolocationCoordinates/heading}} to `NaN`.
+              attribute to a heading, in degrees, or `null` if the
+              implementation cannot provide heading information. If the hosting
+              device is stationary (i.e., the value of the
+              {{GeolocationCoordinates/speed}} attribute is 0), then initialize
+              the {{GeolocationCoordinates/heading}} to `NaN`.
               </li>
             </ol>
           </li>