I&#x27;m not sure what you&#x27;re trying to say. The webkit quote indicates that <i>new experimental features</i> will be unprefixed and behind flags, which is already the policy at Mozilla. For instance as of Firefox 46 (release channel) &quot;grid&quot; is unprefixed (there is no -moz-grid[0]) but behind a flag (layout.css.grid.enabled).<p>&gt; But Mozilla still plans for experimental features to be prefixed:<p>The quote doesn&#x27;t support your interpretation, it only indicates that there <i>are</i> -moz-prefixed experimental properties, just as there <i>are</i> -webkit-prefixed experimental properties.<p>[0] well there is a display: -moz-grid value for display but it&#x27;s a historical XUL property unrelated to the CSS Grid Layout module: <a href="https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=616605#c10" rel="nofollow">https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=616605#c10</a>