- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 07 Feb 2001 09:34:11 +0000
- To: Michael Anderson <michael@research.canon.com.au>
- Cc: xmlschema-dev@w3.org
Michael Anderson <michael@research.canon.com.au> writes: > The Candidate Recommendation added in a new constraining facet called > whitespace, but it doesn't appear to be a facet that does any > constraining. I'm not even sure if it is a facet (but I'm not an english > language expert by any means). The whitespace functionality is a lot more > like a processing instruction than a constraining facet. > > Having it as a facet introduces problems such as when do you apply it? Before validation. > Ie, I have a string " dog" (with a leading space). Is this valid against > the following facets (constraining a string) appearing in this order? > <length value="3"/> > <whitespace value="collapse"/> Yes. > What if we now have (excusing the improper Namespace handling): > <simpleType name="B"> > <restriction base = "string"> > <length value = "3"/> > </restriction> > </simpleType> > <simpleType name = "D" > > <restriction base = "B"> > <whitespace value = "collapse"/> > </restriction> > </simpleType> > A text InfoItem that satisfies D must also satisfy B as D is restricting B, > but this is not the case with our example of " dog". There's a difference here between value spaces and lexical spaces -- the value spaces are properly subsetted, only the lexical space shows the anomaly you identify. > Other problems could possibly arise with the use of the value constraint. > The specs sometimes specify the un-normalized value should be used and at > other times the normalized value. I hope not -- please point out any places using the un-normalized value, they should probably be fixed. > My main problem is that facets change the _value_space_ that defines valid > values, while a whitespace facet changes the _value_ to test in the value > space. Not public discussions, sorry. 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 Wednesday, 7 February 2001 04:34:14 UTC