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Bullard, Claude L (Len) wrote: > 2. What are good reasons for having multiple schemas for the same > instance? > > * To model things by intersection. For example, James Clark's XHTML schemas: one for content models, one to model exclusion exceptions (e.g. that an <a> cannot contain another <a> at any depth.) * Often a schema may be company- or industry-wide, and be little more than a vocabulary with a fairly open or variable content model. Particular uses of that vocabulary may have their own restricted schemas. * When you have variants of some kind: validation in stages, an authoring schema compared to a legacy-data schema, or even to document the effective schema that some application accepts (which may not have complete coverage of all the elements in the notional schema.) Cheers Rick Jelliffe
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