4337 2007-02-19 17:33:14 +0000 Substitution group and abstract 2009-04-21 19:21:45 +0000 1 1 1 Unclassified XML Schema Structures: XSD Part 1 1.0/1.1 both All All CLOSED FIXED resolved P2 normal --- 1 sandygao cmsmcq www-xml-schema-comments oldest_to_newest 14016 0 sandygao 2007-02-19 17:33:14 +0000 Can an abstract element declaration "substitute" another element declaration? The 2 substitution group related constraints give different answers. In the definition of "substitution group" [1], it's clear that abstract element declarations are excluded. But Substitution Group OK (Transitive) doesn't take abstractness into account. Many people consider substitution group as a choice over all members of the "substitution group" of the head. This is currently *not* true given the inconsistency between these constraints. Consider <element name="head" type="date"/> <element name="sub" substitutionGroup="head" abstract="true"/> ... <choice or sequence> <element ref="head"/> <element name="sub" type="int"/> </choice or sequence> It's not clear whether the above <choice> violates "Unique Particle Attribution", and it's not clear whether the <sequence> violates "Element Declaration Consistent". What's the rationale for [1] to exlcude abstract elements from substitution groups? Given the changes in how abstract is handled in schema 1.1 (moving more toward "matched but unfortunately abstract"), maybe [1] should be changed to include abstract elements? [1] http://www.w3.org/TR/xmlschema11-1/#key-eq [2] http://www.w3.org/TR/xmlschema11-1/#cos-equiv-derived-ok-rec 14550 1 cmsmcq 2007-03-27 15:24:45 +0000 On 23 March, the WG accepted a wording proposal to resolve this issue by aligning our definitions and our usage more consistently. The requirement that an element not be abstract is already enforced elsewhere; it does not need to play a role in the definition of the concept 'substitution group'.