update definition of fontBoundingBoxAscent/Descent and emHeightAscent…

source

@@ -62514,21 +62514,29 @@ try {
    <dd>
     <p>The distance from the horizontal line indicated by the <code
     data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the top of the highest
-    bounding rectangle of all the fonts used to render the text, in <span data-x="'px'">CSS
+    bounding rectangle of the first available font used to render the text, in <span data-x="'px'">CSS
     pixels</span>; positive numbers indicating a distance going up from the given baseline.</p>
 
     <p class="note">This value and the next are useful when rendering a background that have to have
     a consistent height even if the exact text being rendered changes. The <code
     data-x="dom-textmetrics-actualBoundingBoxAscent">actualBoundingBoxAscent</code> attribute (and
     its corresponding attribute for the descent) are useful when drawing a bounding box around
     specific text.</p>
+
+    <p class="note">The Implementations of <code data-x="dom-textmetrics-fontBoundingBoxAscent">fontBoundingBoxAscent</code>
+    and <code data-x="dom-textmetrics-fontBoundingBoxDescent">fontBoundingBoxDescent</code> are
+    expected to be equivalent to that of "sTypoAscender" and "sTypoDescender" in
+    <cite>OpenType Specification</cite> <a href="https://docs.microsoft.com/en-us/typography/opentype/spec/os2">OS/2 table</a>.
+    If these are not available, implementations returns "ascender" and "descender" in
+    <a href="https://docs.microsoft.com/en-us/typography/opentype/spec/hhea">hhea table</a>.
+    <ref spec=OPENTABLE></p>
    </dd>
 
    <dt><dfn><code data-x="dom-textmetrics-fontBoundingBoxDescent">fontBoundingBoxDescent</code></dfn> attribute</dt>
 
    <dd><p>The distance from the horizontal line indicated by the <code
    data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the bottom of the lowest
-   bounding rectangle of all the fonts used to render the text, in <span data-x="'px'">CSS
+   bounding rectangle of the first available font used to render the text, in <span data-x="'px'">CSS
    pixels</span>; positive numbers indicating a distance going down from the given
    baseline.</p></dd>
 
@@ -62562,7 +62570,7 @@ try {
 
    <dd><p>The distance from the horizontal line indicated by the <code
    data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the highest top of the em
-   squares in the <span>line box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers
+   squares in the <span>inline box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers
    indicating that the given baseline is below the top of that em square (so this value will usually
    be positive). Zero if the given baseline is the top of that em square; half the font size if the
    given baseline is the middle of that em square.</p></dd>
@@ -62571,31 +62579,31 @@ try {
 
    <dd><p>The distance from the horizontal line indicated by the <code
    data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the lowest bottom of the em
-   squares in the <span>line box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers
+   squares in the <span>inline box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers
    indicating that the given baseline is above the bottom of that em square. (Zero if the given baseline
    is the bottom of that em square.)</p></dd>
 
    <dt><dfn><code data-x="dom-textmetrics-hangingBaseline">hangingBaseline</code></dfn> attribute</dt>
 
    <dd><p>The distance from the horizontal line indicated by the <code
    data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the hanging baseline of the
-   <span>line box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers indicating that
+   <span>inline box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers indicating that
    the given baseline is below the hanging baseline. (Zero if the given baseline is the hanging
    baseline.)</p></dd>
 
    <dt><dfn><code data-x="dom-textmetrics-alphabeticBaseline">alphabeticBaseline</code></dfn> attribute</dt>
 
    <dd><p>The distance from the horizontal line indicated by the <code
    data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the alphabetic baseline of
-   the <span>line box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers indicating
+   the <span>inline box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers indicating
    that the given baseline is below the alphabetic baseline. (Zero if the given baseline is the
    alphabetic baseline.)</p></dd>
 
    <dt><dfn><code data-x="dom-textmetrics-ideographicBaseline">ideographicBaseline</code></dfn> attribute</dt>
 
    <dd><p>The distance from the horizontal line indicated by the <code
    data-x="dom-context-2d-textBaseline">textBaseline</code> attribute to the ideographic baseline of
-   the <span>line box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers indicating
+   the <span>inline box</span>, in <span data-x="'px'">CSS pixels</span>; positive numbers indicating
    that the given baseline is below the ideographic baseline. (Zero if the given baseline is the
    ideographic baseline.)</p></dd>
   </dl>
@@ -120767,6 +120775,9 @@ INSERT INTERFACES HERE
    <dt id="refsOPENSEARCH">[OPENSEARCH]</dt>
    <dd><cite><a href="http://www.opensearch.org/Specifications/OpenSearch/1.1#Autodiscovery_in_HTML.2FXHTML">Autodiscovery in HTML/XHTML</a></cite>. In <cite>OpenSearch 1.1 Draft 4</cite>, Section 4.6.2. OpenSearch.org.</dd>
 
+   <dt id="refsOPENTABLE">[OPENTABLE]</dt>
+   <dd>(Non-normativs) <cite><a href="https://docs.microsoft.com/en-us/typography/opentype/spec">OpenType Specification</a></cite>. Microsoft</dd>
+
    <dt id="refsORIGIN">[ORIGIN]</dt>
    <dd>(Non-normative) <cite><a href="https://tools.ietf.org/html/rfc6454">The Web Origin Concept</a></cite>, A. Barth. IETF.</dd>
 
@@ -122009,6 +122020,7 @@ INSERT INTERFACES HERE
   Yay295,
   Ye-Kui Wang,
   Yehuda Katz,
+  Yi Xu
   Yi-An Huang,
   Yngve Nysaeter Pettersen,
   Yoav Weiss,