This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
HT: Identity constraints are described as applying to "an element or attribute node with a simple type", but it's not clear from this whether an element with a simpleContent complex type is OK (which it should be, in my opinion). See http://lists.w3.org/Archives/Public/www-xml-schema-comments/2003JanMar/0049.html
Resolved at the 2003-09-10 telecon to classify as clarification w/erratum, clarifying that the use of simple type is intended to also cover simpleContent.