An attribute use that references a global attribute carrying a `fixed` value
constraint may not contradict it (au-props-correct.2): a `fixed` on the
reference whose value differs from the global's, or a `default` on a reference
to a fixed attribute, is invalid. A reference that omits its own value
constraint inherits the global's and stays valid.
The two `fixed` values are compared in the attribute type's value space, so a
value-equal pair written in different lexical forms (`01` for `1`) is not
flagged. The global is resolved by local name and only checked once its own
namespace matches the reference's resolved namespace, so a same-local-name
attribute imported from another namespace cannot surface as the wrong global
and contradict a valid reference.
Caught two invalid schemas: XSTS invalid-schemas-accepted 232 -> 230, no other
bucket moved.
Mihaela Mihaljevic
c80a8e06c4