- From: Jeni Tennison <jeni@jenitennison.com>
- Date: Wed, 1 May 2002 18:53:50 +0100
- To: "Morris Matsa" <mmatsa@us.ibm.com>
- CC: Yuri de Wit <yuri.dewit@metaserver.com>, "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
Hi Morris, > I believe that necessarily infinitely recursive unsatisfiable types > are forbidden in Schemas. This question was answered about a year > ago on this list [1], and the part of the schema spec quoted then > was [2]. Please tell me if I'm wrong. Hmm... I don't think that the definition of an emptiable group (http://www.w3.org/TR/xmlschema-1/#cos-group-emptiable) relates to the question of infinitely recursive unsatisfiable types. As far as I can tell, the only places in which this Schema Component Constraint is used is when assessing whether it's OK to derive one type from another type, and whether an element's default/fixed value is OK. There might be something else specifying a constraint like this somewhere, of course, but I don't think that's it. If there were such a constraint, I guess it would be a constraint on model groups that stated that a model group whose minimum effective total range is more than 0 cannot contain an element particle at any level whose minimum effective total range is more than 0 and whose type's content involves that model group at any level. But I can't see such a constraint anywhere. Cheers, Jeni --- Jeni Tennison http://www.jenitennison.com/
Received on Wednesday, 1 May 2002 13:53:56 UTC