- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 06 Nov 2001 16:29:24 +0000
- To: Mark Feblowitz <mfeblowitz@frictionless.com>
- Cc: "Xmlschema-Dev (E-mail)" <xmlschema-dev@w3.org>
Mark Feblowitz <mfeblowitz@frictionless.com> writes: > I sent a similar message to Henry, but I also thought it would be useful to > break it open for wider discussion. > > I am part of a team that is developing the Open Application Group's XML > Schema version of the OAGIS standard. Before we commit the grievous sin of > including illegal Schema constructs in a proposed standard(!), we thought it > a good idea to ask about particular usage that we're unsure of. > > There seem to be diverse interpretations regarding allowable derivations of > complex types by restriction. The issue at hand is that of adding a new > child element to a complex type that has been derived by restriction. I'm not aware of anyone ever claiming this was allowed by the REC. It's not. > Our understanding, based on reading the Schema Structures spec, is > that this is not allowed. But XML Spy, Xerces, and XSV allow this > behavior. XSV's documentation [1] lists: "Detailed enforcement of derivation by restriction" in the Not Implemented Yet section. The key invariant, which you don't need a validator to check, is that every member of the derived type must be a member of the base type. Adding a new child clearly breaks that. ht [1] http://www.ltg.ed.ac.uk/~ht/xsv-status.html -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh W3C Fellow 1999--2001, part-time member of W3C Team 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440 Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk URL: http://www.ltg.ed.ac.uk/~ht/
Received on Tuesday, 6 November 2001 11:28:30 UTC