Message
xref in a contrib should point to an element in the same scope: an element in the same contrib-group, an element in author-notes, or a contrib-group element in the same article-meta or front-stub
Rule XPath:
This rule ASSERTS the following, raising an alert if FALSE:
every $rid in tokenize(@rid, '\s+') satisfies exists((
ancestor::contrib-group[1]/*,
ancestor::contrib-group/following-sibling::author-notes/*,
ancestor::article-meta/contrib-group,
ancestor::front-stub/contrib-group)[@id = $rid] )