Within one complex type's content model, two element declarations with the same
name must have the same type definition. Two same-name elements with different
types were accepted. elementDeclsConsistentErrors collects element particles
across the content model -- descending through model groups and the content-
derivation wrappers, but never into an element's own nested type, which is a
separate content model -- and flags a name seen with more than one distinct type
key (a type reference by local name, a distinct token per inline type, or the
untyped ur-type).
Modeled clean-room on Xerces (libxml2 enforces this only partially). Substitution-
group expansion is not folded in, an accepted under-rejection.
XSTS: invalid schemas accepted 925 to 909 (-16); valid schemas rejected held at
72; instance buckets unchanged.