The attribute sibling of the content-model table. Each XSD component admits a
fixed set of attributes; an unprefixed attribute outside that set (a typo like
nullable, a stray foo, name on a sequence) was accepted because nothing checked
attribute applicability. allowedAttributes now lists each component's admitted
unprefixed attributes (the permissive union of global and local use), and
attributeApplicabilityErrors rejects the rest, plus ref co-occurring with name
or type.
Foreign (prefixed) attributes and namespace declarations are the schema author's
own and are not checked, so no valid schema is rejected.
XSTS: invalid schemas accepted 956 to 925 (-31); valid schemas rejected held at
72; instance buckets unchanged.