Merge branch 'master' of https://github.com/WICG/spatial-navigation

Author: Jihye Hong

index.bs

@@ -1112,7 +1112,7 @@ including all graphical transformations, such as <a>relative positioning</a> or
 
 The <dfn>boundary box</dfn> of an object is defined as follows:
 * if the object is a point, the boundary box is that point
-* if the object is an element, the boundary box is the <a>border box</a> of the element's <a>principal box</a>.
+* if the object is a [=box=] or [=box fragment=], the boundary box is the <a>border box</a> of that box or fragment.
 * if the object is a <a>focusable area</a> which is not an element, the boundary box is the axis-aligned the bounding box of that <a>focusable area</a>
 
 Issue(w3c/csswg-drafts#2324): CSS should have a term for “border box taking into account corner shaping properties like border-radius”.
@@ -1123,8 +1123,9 @@ To <dfn lt="find focusable areas | finding focusable areas">find focusable areas
 with an optional <var>visibleOnly</var> argument that defaults to <code>true</code>,
 follow the following steps:
 
-1. Let <var>focusables</var> be the <a spec=infra for="/">set</a> of all the <a>focusable areas</a> that are descendants of <var>C</var>.
-2. The UA should <a spec=infra for=set>remove</a> from <var>focusables</var> elements whose <a element-attr spec=html><code>tabindex</code></a> attribute is set to a negative value.
+1. Let <var>focusables</var> be the <a spec=infra for="/">set</a> of all the <a>focusable areas</a> whose [=DOM anchor=] are descendants of <var>C</var>.
+    In the case of [=boxes=] with several [=box fragments=], each [=box fragment=] is considered separately.
+2. The UA should <a spec=infra for=set>remove</a> from <var>focusables</var> items that have a [=DOM anchor=] whose <a element-attr spec=html><code>tabindex</code></a> attribute is set to a negative value.
 
     Note: This is a "SHOULD" in order to mirror the exclusion of elements with negative tabindex
     from the <a>sequential focus navigation order</a> as defined in [[HTML#the-tabindex-attribute]].
@@ -1175,7 +1176,7 @@ follow the following steps:
     * the viewport if <var>starting point</var> is a <a>Document</a>,
     * the <a>border box</a> of <var>starting point</var> otherwise.
 4. Let <var>insiders</var> be the subset of <var>candidates</var> items
-    who are descendants of <var>starting point</var>
+    whose [=DOM anchor=] are descendants of <var>starting point</var>
     and whose <a>boundary box</a>'s
     * top edge is below the top edge of <var>insideArea</var> if <var>D</var> is <code>down</code>
     * bottom edge is above the bottom edge of <var>insideArea</var> if <var>D</var> is <code>up</code>