- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 14 Sep 2001 12:51:38 +0100
- To: "Gregory M. Messner" <gmessner@breezefactor.com>
- Cc: "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
"Gregory M. Messner" <gmessner@breezefactor.com> writes: > Following is the definition of <restriction> on a simpleType (from XML > Schema Part 1: Structures): > > <restriction > base = QName > id = ID > {any attributes with non-schema namespace . . .}> > Content: (annotation?, (simpleType?, (minExclusive | minInclusive | > maxExclusive | maxInclusive | totalDigits | fractionDigits | length | > minLength | maxLength | enumeration | whiteSpace | pattern)*)) > </restriction> > > Based on this definition, is the following XML Schema snippet valid? > > <simpleType name="CryptoBinary"> > <restriction base="base64Binary"></restriction> > </simpleType> Yes. > Notice that the restriction has no content. If this is valid, then is the > intent to just extend the "base64Binary" builtin type? I don't see any sign of extension here. > Or assign a different name to the "base64Binary" builtin type? I presume that's the purpose. > I thought <restriction> was intended to restrict a new datatype to a > *subset* of an existing type? {a, b, c} _is_ a subset of {a, b, c}. In discussing the overall architecture, the Structures part of the REC says: "Any property value identified as a . . . subset of some set may be equal to that set, unless a proper . . . subset is explicitly called for." This is the normal usage of these words/phrases in set theory, sorry if it confused you. ht -- 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 Friday, 14 September 2001 07:51:06 UTC