2112 2005-09-09 15:13:35 +0000 R-123: A question about redefining redefines 2009-04-21 19:25:01 +0000 1 1 1 Unclassified XML Schema Structures: XSD Part 1 1.0 only All All CLOSED WORKSFORME P2 normal --- 1 sandygao ht www-xml-schema-comments oldest_to_newest 6033 0 sandygao 2005-09-09 15:13:35 +0000 There are situations in which the redefinition of a type, and the subsequent redefinition of the redefined type, are desirable. One such case is where a schema user would like to extend a type, not just from the original source but based on the extension of another schema user's extension (Company C extends type T from Company B, who picked it up from Company A and redefined it). It appears that this is discouraged in the Rec. From 4.2.2: "In all cases there must be a top-level definition item of the appropriate name and kind in the redefined schema document. NOTE: The above is carefully worded so that multiple equivalent redefining of the same schema document will not constitute a violation of clause 2 of Schema Properties Correct (3.15.6) , but applications are allowed, indeed encouraged, to avoid redefining the same schema document in the same way more than once to forestall the necessity of establishing identity component by component (although this will have to be done for the individual redefinitions themselves)." Some validators require that the redefined schema contain a type definition for a type that is to be redefined - that a redefinition is not sufficient. So it is not possible to redefine a redefined type. So the question is, is this something that is likely to change, or will validators vary on whether or not they support cascading redefines? 6034 1 sandygao 2005-09-09 15:14:10 +0000 Henry's response: Unfortunately the term 'top-level' is not formally defined in the REC. There are a number of places where things such as "all the top-level (i.e. named) components. . ." appear, so it's clear that what's meant is (XML representations of) named components which appear in one of the sets of definitions/declarations of the schema component itself. On that basis, redefs of redefs are OK, and were certainly intended to be. An erratum is in order, in my opinion. See: http://lists.w3.org/Archives/Public/www-xml-schema-comments/2002JanMar/0513.html Resolution: Discussed and resolved at the June 12, 2003 telecon: RESOLVED: to classify R-123 as clarification without erratum. ACTION: Sandy Gao to send Mark Feblowitz a copy of SG's note explaining the logic of our decision.