Additional work on changing map state via scripting.

Author: NickFitz

index.html

@@ -5341,18 +5341,34 @@ <h5>Conclusion</h5>
 </ul>
 </section>
 
-<section id="capability-pan-map-or-re-centre-map" data-ucr-role="capability">
-<h4>Pan a map or re-centre a map</h4>
+<section id="capability-pan-zoom-or-re-centre-map" data-ucr-role="capability">
+<h4>Pan, zoom or re-centre a map</h4>
 <p>
-Description to follow
+Developers expect to be able to control a map by changing its centre and/or zoom level,
+and may also wish to support the capability of resetting a map to its view as originally presented.
+If the map view cannot be dynamically modified by an application,
+as opposed to changes by direct user interaction with the map,
+then it offers fewer advantages over a static map view.
+</p>
+<p>
+It is usually also desirable that such changes can be accomplished in a manner that gives sufficient
+visual feedback to the user that a change is occurring,
+for example by animating the transition rather than simply redrawing the map with the new view,
+which may not be immediately noticeable to the user.
+</p>
+<p>
+Accessibility is an important consideration when the state of a map is altered dynamically.
+Thought should be given to how the change can be made known to assistive technologies so that the user
+is fully informed and thus cognisant of the current state of the map at all times.
 </p>
 <p class="issue discussion" data-number="67">
 Discuss this section on GitHub.
 </p>
 
 <h5>Existing implementations</h5>
 <p>
-Existing implementation support:
+All the reviewed JavaScript API implementations support changing the bounds, centre, and zoom level of a map,
+and allow such transitions to be animated.
 </p>
 <dl data-ucr-role="implementation-notes">
 <!-- Use dt elements to name the implementation, using the id string to create an auto-link.
@@ -5368,8 +5384,12 @@ <h5>Existing implementations</h5>
 <dt>leaflet-api</dt>
 <dt>open-layers-api</dt>
 <dt>d3-geographies-api</dt>
-<dd><a>not applicable</a>:
+<dd><a>full support</a>:
 <!-- details about what is/isn't supported -->
+<p>
+Animated transitions are supported by calling specific methods with names such as <code>flyTo</code>
+or via a Boolean parameter to a more general method such as <code>setView</code>.
+</p>
 </dd>
 </dl>
 
@@ -5394,7 +5414,8 @@ <h5>Conclusion</h5>
 See examples.
 -->
 <p>
-Based on the limited data, we are <a data-ucr-role="conclusion">undecided</a> about whether this should be a requirement.
+As this is capability is required for any dynamic update of a map view such as would be expected of a map-based application,
+it is a <a data-ucr-role="conclusion">requirement</a> for embedded web maps.
 </p>
 <ul data-ucr-role="conclusion-notes">
 <!-- bullet-point notes summarizing implementation details / blocking issues.