A complex type that records no base of its own derives only from xsd:anyType, so
it cannot validly substitute (cvc-elt.4.3.2.1) for an element whose declared type
is a more specific complex type. The not-derived check required the substitute to
be present in the derivation backbone, so naming the declared type's own complex
ancestor, or an unrelated baseless complex type, via xsi:type was accepted.
notDerivedSubstitutionError now treats a complex substitute as in scope even when
it is absent from the backbone: its non-derivation from a non-ur declared type is
certain (a baseless complex type derives only from anyType, and any real
extension/restriction chain is recorded in the backbone, where derivationMethods
finds it). An atomic substitute must still be in the backbone, so a built-in
stays silent. The declared guard excludes the ur-types, so a baseless complex
substitute under an anyType declaration is admitted; a genuine extension or
restriction substitute is accepted.
invalid-instances-accepted 60 to 53, no false positive (valid-instances-rejected
and valid-schemas-rejected held at 0), no other bucket moved. An adversarial
review exercised deep, cross-namespace, redefine, and element-ref-path derivation
chains plus anyType-declared baseless substitutes, and found no over-rejection.
Mihaela Mihaljevic
b3a2bcfe6a