• From: "Costello, Roger L." <costello@m...>
• To: <xml-dev@l...>
• Date: Wed, 17 Oct 2007 10:01:29 -0400

Hi Folks,
 
The current version of the XML Schemas specification contains a
schema-for-schemas.  The schema-for-schemas is expressed using the XML
Schema language.  But there are some things that the schema-for-schema
cannot express using the XML Schema language.  

For example, it cannot express this rule: if an element declaration has
a type attribute, it cannot have a complexType or simpleType child
element.  This is an example of a co-constraint, which the current XML
Schema specification does not support.  

Consequently, for things like the above co-constraint the
schema-for-schemas resorts to comments containing English prose.

As I understand it, the next version of XML Schemas will provide a way
to express co-constraints.  So, in the next version of XML Schemas will
the schema-for-schemas be expressible entirely using the XML Schema
language? 

/Roger

• Follow-Ups:
  • RE: Will the next version of XML Schema have a schema-for-schemas that is standalone (no English prose needed to describe constraints in the language)?
    • From: "Michael Kay" <mike@s...>