Merge duplicative text related to id.

Author: msporny

index.html

@@ -1352,30 +1352,13 @@ <h3>Identifiers</h3>
 allows for the expression of statements about specific things in the
 [=verifiable credential=] and is set by an [=issuer=] when expressing
 objects in a [=verifiable credential=] or a [=holder=] when expressing
-objects in a [=verifiable presentation=]. Example `id` values
+objects in a [=verifiable presentation=]. The `id` [=property=] expresses an
+identifier that others are expected to use when expressing statements about a
+specific thing identified by that identifier. Example `id` values
 include UUIDs (`urn:uuid:0c07c1ce-57cb-41af-bef2-1b932b986873`), HTTP URLs
 (`https://id.example/things#123`), and DIDs (`did:example:1234abcd`).
         </p>
 
-        <p>
-<em>If</em> the `id` [=property=] is present:
-        </p>
-
-        <ul>
-          <li>
-The `id` [=property=] MUST express an identifier that others are
-expected to use when expressing statements about a specific thing identified
-by that identifier.
-          </li>
-          <li>
-The `id` [=property=] MUST NOT have more than one value.
-          </li>
-          <li>
-The value of the `id` [=property=] MUST be a [=URL=] which
-MAY be dereferenced.
-          </li>
-        </ul>
-
         <p class="note">
 Developers should remember that identifiers might be harmful in scenarios
 where pseudonymity is required. Developers are encouraged to read Section
@@ -1392,10 +1375,10 @@ <h3>Identifiers</h3>
         <dl>
           <dt><dfn class="export">id</dfn></dt>
           <dd>
-The value of the `id` [=property=] MUST be a single [=URL=].
-It is RECOMMENDED that the [=URL=] in the `id` be one which, if
-dereferenced, results in a document containing machine-readable information
-about the `id`.
+The `id` [=property=] is OPTIONAL. If present, the value of the `id`
+[=property=] MUST be a single [=URL=] which MAY be dereferenced. It is
+RECOMMENDED that the [=URL=] in the `id` be one which, if dereferenced, results
+in a document containing machine-readable information about the `id`.
           </dd>
         </dl>