Add SnapEvent Definition

Patchset 5: Per-axis SnapEvent targets, link 'proximity', improve
text clarity

Author: DavMila

css-scroll-snap-2/Overview.bs

@@ -318,9 +318,9 @@ Snap Events {#snap-events}
 		</li>
 		</ul>
 	</li>
-	<li> (for snap containers with proximity strictness) at the end of a scroll in which
-		the snap container scrolls and settles into (or out of) the
-		proximity range of a snap area in either axis.
+	<li> (for snap containers with ''scroll-snap-type/proximity'' strictness) at the end of a scroll in which
+		the snap container scrolls and settles into (or out of) a
+		snap area's range of proximity snap positions in either axis.
 	</li>
 	<li> if there is a change to a snap container's style such that it goes from having a
 		non-'none' value for scroll-snap-type to having a 'none' value or vice versa.
@@ -329,9 +329,13 @@ Snap Events {#snap-events}
 		snapped to changes, regardless of whether there is a change in scroll position
 		after the layout change.
 	</li>
+	</ol>
 
 	Although, snapping occurs when a snap container is first
-	laid out, snapchanged should not be triggered by this initial layout snap.
+	laid out, {{snapchanged}} should not be triggered by this initial layout snap.
+	Scrolling operations always lead to {{scrollend}} events being fired. If a scrolling operation
+	also results in a {{snapchanged}} event being fired, the {{snapchanged}} event should be fired
+	before the {{scrollend}} event.
 
 <h4 id="snapchanging"> snapchanging </h4>
 	{{snapchanging}} is dispatched when the snap area to which a
@@ -346,7 +350,7 @@ Snap Events {#snap-events}
 		the snap position that will eventually be snapped to after the scroll animation's
 		target offset is reached.
 	* In the latter case, the user agent should evaluate whether snapchanging should
-		be triggered based on the snap position that would eventually be snapped to if
+		be triggered based on the snap position that would be snapped to if
 		the scroll is ended at the current scroll position (determined by the user's input).
 
 	Note that since snapchanging gives the web page hints about future snapping,
@@ -361,24 +365,31 @@ SnapEvent interface
 <pre class="idl">
 			[Exposed=Window]
 			interface SnapEvent : Event {
-				readonly attribute NodeList snapTargets;
+				readonly attribute Node snapTargetBlock;
+				readonly attribute Node snapTargetInline;
 			};
 </pre>
 
 <dl>
-		<div dfn-type=attribute class=attributes dfn-for="SnapEvent">
-		: <dfn>snapTargets</dfn>
+			<div dfn-type=attribute class=attributes dfn-for="SnapEvent">
+		: <dfn>snapTargetBlock</dfn>
 		::
-			The list of elements that the snap container is snapped
-			to at the snap position for the associated snap event. For
-			snapchanged events, the snap position is the position already
-			realized by	the snap container after a scroll snap. For snapchanging
-			events it is the snap position that the scroller will eventually
-			snap to when the scrolling operation ends.
-
-			This list includes one element for the block axis and/or one element for the inline axis.
-			(TODO: link spec on how the target is picked).
+			The element that the snap container is snapped to in the block axis
+			at the snap position for the associated snap event. 
 			</div>
+			<div dfn-type=attribute class=attributes dfn-for="SnapEvent">
+		: <dfn>snapTargetInline</dfn>
+		::
+			The element that the snap container is snapped to in the inline axis
+			at the snap position for the associated snap event.
+			</div>
+
+			(TODO: link spec on how snap containers pick snap targets).
+
+		For {{snapchanged}} events, the snap position is the position already
+		realized by	the snap container after a scroll snap. For {{snapchanging}}
+		events it is the snap position that the scroller will eventually
+		snap to when the scrolling operation ends.
 
 	</dl>