A particle restriction whose restricting element has a union-typed base element
was checked by structural member subsetting: PureXML accepted a separately
declared union whenever its members were a subset of the base union's. That is
not the spec's derivation relation. The NameAndTypeOK type clause (XSD 1.0
section 3.9.6) requires the restricting element's type to be validly derived
from the base element's type per Type Derivation OK (Simple), cos-st-derived-ok.
The restricting type is now valid over a union base only if it is the base
type, derives from it through a declared restriction chain, or (clause 2.2.4)
validly derives from one of the union's member types. Scoped to the
element-restriction path, so no attribute or simple-type derivation check moved.
Catches particlesIk011 (a fresh union(integer) is not a restriction of
union(integer, string)): XSTS invalid-schemas-accepted 9 to 8, valid-schemas-
rejected held at 0 over the full corpus (the cardinal no-over-rejection check).
Disclosed: particlesIk025/Ik027, where the restricting type derives from a
union member, are accepted per cos-st-derived-ok 2.2.4, a contested reading
their XSTS invalid expectation does not share. An in-repo test that asserted
the old structural-subset behavior is corrected.
Mihaela Mihaljevic
0af92bcf8d