Mark definition of "media timed events" as dfn

The document tried to reference the definition of "media timed events" but
that definition was not marked as being a definition. The update also adds
references to the definition from the various sections that use it.

index.html

@@ -89,7 +89,7 @@ <h2>Introduction</h2>
         events synchronized to audio or video media, specifically for both
         <a>out-of-band</a> event streams and <a>in-band</a> discrete events
         (for example, MPD and <code>emsg</code> events in MPEG-DASH).
-        These <em>media timed events</em> can be used to support use cases
+        These <dfn data-lt="media timed event">media timed events</dfn> can be used to support use cases
         such as dynamic content replacement, ad insertion, or presentation of
         supplemental content alongside the audio or video, or more generally,
         making changes to a web page, or executing application code triggered
@@ -126,7 +126,7 @@ <h2>Terminology</h2>
     <section>
       <h2>Use cases</h2>
       <p>
-        Media timed events carry metadata that is related to points in time,
+        <a>Media timed events</a> carry metadata that is related to points in time,
         or regions of time on the <a>media timeline</a>, which can be used to
         trigger retrieval and/or rendering of web resources synchronized with
         media playback. Such resources can be used to enhance user experience
@@ -146,7 +146,7 @@ <h3>Dynamic content insertion</h3>
           A media content provider wants to allow insertion of content,
           such as personalised video, local news, or advertisements,
           into a video media stream that contains the main program content.
-          To achieve this, media timed events used to describe the points
+          To achieve this, <a>media timed events</a> used to describe the points
           on the <a>media timeline</a>, known as splice points, where switching
           playback to inserted content is possible.
         </p>
@@ -178,7 +178,7 @@ <h3>Audio stream with titles and images</h3>
       <section>
         <h3>Control messages for media streaming clients</h3>
         <p>
-          A media streaming server uses <a>media timed events<a> to send control
+          A media streaming server uses <a>media timed events</a> to send control
           messages to media client library, such as <a href="https://github.com/Dash-Industry-Forum/dash.js">dash.js</a>.
           Typically segmented streaming protocols such as HLS and MPEG-DASH make
           use of a manifest document that informs the client of the available
@@ -274,7 +274,7 @@ <h3>Presentation of auxiliary content in live media</h3>
       <h2>Related industry specifications</h2>
       <p>
         This section describes existing media industry specifications and
-        standards that specify carriage of media timed events, or otherwise
+        standards that specify carriage of <a>media timed events</a>, or otherwise
         provide requirements for web APIs related to the triggering of media
         timed events.
       </p>
@@ -311,7 +311,7 @@ <h3>MPEG-DASH</h3>
           MPEG-2 transport stream.
         </p>
         <p>
-          In MPEG-DASH, media timed events may be delivered either
+          In MPEG-DASH, <a>media timed events</a> may be delivered either
           <a>in-band</a> or <a>out-of-band</a>:
         </p>
         <ul>
@@ -666,7 +666,7 @@ <h3>Synchronized rendering of web resources</h3>
         <p>
           Another approach to synchronizing rendering of web content to media
           playback is to use the <code>timeupdate</code> event, and for the
-          web application to manage the media timed events to be triggered,
+          web application to manage the <a>media timed events</a> to be triggered,
           rather than add use the text track cue APIs in [[HTML]]. This has the
           same synchronization limitations as described above, because the 250
           millisecond update rate specified in <em>time marches on</em> is too
@@ -691,7 +691,7 @@ <h3>Synchronized rendering of web resources</h3>
       <h2>Recommendations</h2>
       <p>
         This section describes recommendations from the Media &amp; Entertainment
-        Interest Group for the development of a generic media timed event API,
+        Interest Group for the development of a generic <a>media timed event</a> API,
         and associated synchronization considerations.
       </p>
       <section>
@@ -728,7 +728,7 @@ <h3>Event triggering</h3>
         </p>
         <ul>
           <li>
-            Generate a JavaScript event when an <a>in-band</a> media timed event
+            Generate a JavaScript event when an <a>in-band</a> <a>media timed event</a>
             is parsed from the media container or media stream (DAInty Mode 1).
           </li>
           <li>
@@ -749,7 +749,7 @@ <h3>Event triggering</h3>
         <h3>In-band event processing</h3>
         <p>
           We recommend updating [[INBANDTRACKS]] to describe handling of
-          <a>in-band</a> media timed events supported on the web platform,
+          <a>in-band</a> <a>media timed events</a> supported on the web platform,
           following a registry approach with one specification per media format
           that describes the event details for that format.
         </p>
@@ -769,7 +769,7 @@ <h3>Synchronization</h3>
           In order to acheive greater synchronization accuracy between media
           playback and web content rendered by an application, the <em>time
           marches on</em> steps in [[HTML]] should be modified to allow delivery
-          of media timed event start time and end time notifications within 20
+          of <a>media timed event</a> start time and end time notifications within 20
           milliseconds of their positions on the <a>media timeline</a>.
         </p>
       </section>