[css-conditional-4] Add font-format to @supports

Author: svgeesus

css-conditional-4/Overview.bs

@@ -32,7 +32,7 @@ Default Highlight: css
 <h2 id="introduction">Introduction</h2>
 
 This is currently an early draft of the things that are <em>new</em> in level 4.
-The features in level 3 are still defined in [[css3-conditional]]
+The features in level 3 are still defined in [[css-conditional-3]]
 and have not yet been copied here.
 
 It adds extensions to the ''@supports'' rule
@@ -67,14 +67,18 @@ Issue: In the future, copy the contents of [[css-conditional-3]] into this docum
 This level of the specification extends the <<supports-feature>> syntax as follows:
 
 <pre class="prod def" nohighlight>
-	<dfn>&lt;supports-feature></dfn> = <<supports-selector-fn>> | <<supports-font-technology-fn>> | <<supports-decl>>
+	<dfn>&lt;supports-feature></dfn> = <<supports-selector-fn>> | <<supports-font-technology-fn>>
+                    | <<supports-font-format-fn>> | <<supports-decl>>
 	<dfn>&lt;supports-selector-fn></dfn> = selector( <<complex-selector>> )
   <dfn>&lt;supports-font-technology-fn></dfn> = font-technology ( <<font-technology>> )
   <dfn>&lt;font-technology></dfn> = [ features-opentype | features-aat | features-graphite
                       | color-colrv0 | color-colrv1 | color-svg | color-sbix | color-cbdt
                       | variations | palettes | incremental ]
+  <dfn>&lt;supports-font-format-fn></dfn> = font-format ( <<font-format>> )
+  <dfn>&lt;font-format</dfn> = [ collection | embedded-opentype | opentype | svg | truetype | woff | woff2 ]
 </pre>
 
+
 : <<supports-selector-fn>>
 ::
 	The result is true if the UA
@@ -87,6 +91,11 @@ This level of the specification extends the <<supports-feature>> syntax as follo
     <a href="dfn-support-font-technology">supports the font technology</a>
     provided as an argument to the function.
 
+: <<supports-font-format-fn>>
+::
+    The result is true if the UA
+    <a href="#dfn-support-font-format">supports the font format</a>
+    provided as an argument to the function.
 
 <h3 id="support-definition-ext">Extensions to the definition of support</h3>
 
@@ -99,7 +108,13 @@ parse error), and that selector doesn't contain
 A CSS processor is considered to
 <dfn export for=CSS id="dfn-support-font-technology">support a font technology</dfn>
 when the text and layout processing engine ingesting
-this CSS text is capable of utilising the specified font-technology
+this CSS text is capable of utilising the specified <<font-technology>>
+in layout and rendering.
+
+A CSS processor is considered to
+<dfn export for=CSS id="dfn-support-font-format">support a font format</dfn>
+when the text and layout processing engine ingesting
+this CSS text is capable of utilising the specified <<font-format>>
 in layout and rendering.
 
 <h2 id="when-rule">Generalized Conditional Rules: the ''@when'' rule</h2>