[css-anchor-position-1] anchor-scope:all is effectivley a tree-scoped name. #10525

Author: tabatkins

css-anchor-position-1/Overview.bs

@@ -270,6 +270,12 @@ Values have the following meanings:
 		and limits descendants to only match [=anchor names=]
 		to [=anchor elements=] within this subtree.
 
+		This value only affects [=anchor names=] in the same tree scope,
+		as if it were a [=tree-scoped name=].
+		(That is, ''anchor-scope: all'' acts identically
+		to ''anchor-scope: --foo, --bar, ...'',
+		listing all relevant [=anchor names=].)
+
 	<dt><dfn><<dashed-ident>></dfn>
 	<dd>
 		Specifies that a matching [=anchor name=] defined by this element or its descendants--