A redefinition of an attribute group may not ADD an attribute the original does
not declare (a superset is not a restriction, src-redefine / cos-ct-restricts);
schM3 (redeclaring the original's attributes plus a new b4) is now rejected. The
base is resolved by namespaced identity with a {}name chameleon fallback for a
no-targetNamespace redefined schema.
False-positive-free: the added-attribute check runs only when the original's
attribute set is fully known from its direct declarations and the redefinition
carries no attributeGroup reference (a self-reference brings in the original's
attributes, so declaring more alongside it is a valid redefine, not an addition,
W3C attgC007/attgC038/groupB018, test75083/xsd003b), and a use=prohibited
attribute the base lacks forbids rather than permits a name, so it does not widen
the usable set and is left alone.
XSTS invalid-schemas-accepted 51 -> 49, no false positive (valid-schemas-rejected
and valid-instances-rejected held at 0; five self-reference over-rejections were
caught by the gate and one prohibited-attribute over-rejection by an adversarial
critic, all fixed before commit), no other bucket moved.
Mihaela Mihaljevic
afad5f822c