added detail on full-range alpha

are always full-range and

index.html

@@ -870,8 +870,8 @@ <h2>Color spaces</h2>
       to be applied (see <a href="#C-GammaAppendix"></a>). However, color-aware applications will prefer one of the first three
       methods, while color-unaware applications will typically ignore all four methods.</p>
 
-      <p><a>Gamma</a> correction is not applied to the alpha channel, if present. Alpha samples always represent a linear fraction
-      of full opacity.</p>
+      <p><a>Gamma</a> correction is not applied to the alpha channel, if present. Alpha samples are always full-range and represent 
+      a linear fraction of full opacity.</p>
 
       <p>Mastering metadata may also be provided</p>
     </section>