[css-images-3] Ambiguous image URLs that are fragment-only URLs aren'…

…t treated as <image>. #383

css-images-3/Overview.bs

@@ -176,7 +176,9 @@ Image References: the ''url()'' notation {#url-notation}
 	An <dfn export for=CSS>ambiguous image URL</dfn> is
 	a <<url>> value that can be interpreted
 	as either an <<image>> or an element reference.
-	If an [=ambiguous image URL=] has a fragment
+	If an [=ambigous image URL=] is a [[css-values-3#local-urls|fragment-only URL]],
+	then it must be treated as an element reference.
+	Otherwise, if the [=ambiguous image URL=] has a fragment
 	that references an element in the resource
 	that is an appropriate type of element for the context in which the <<url>> appears
 	(such as a <{mask}> element for the 'mask-image' property),