Re: [xml-dev] Data Interoperability ... Why do some XML vocabulariesspe

[Michael Kay <mike@saxonica.com>]

 >Why do some XML vocabularies specify meaning +  behavior whereas 
others specify only meaning?

Because some messages are informational (John likes cycling) and some 
are imperative (Send reinforcements!), and XML mirrors real life. Some 
messages of course fall between these extremes (It would be nice if you 
phoned home more often).

> EXAMPLES
>
>     XML Schema: the XML Schema specification describes the
>     meaning of<element>  as well as its behavior:
>
>     -<element>  is a specification of an information item.
>       That is meaning.
>
>     - A compliant tool must validate that the instance
>       document contains an element with the specified name,
>       type, and occurrences. That is behavior.
>    

The XSD specification defines conformant schema documents and conformant 
instance validators. It never says that instance validation is the only 
use you can make of a schema document; on the contrary, the design of 
the language is expressly based on the assumption that it can be used 
for many purposes.

>     XSLT: the XSLT specification describes the
>     meaning of<for-each>  as well as its behavior:
>
>     -<for-each>  identifies a collection of nodes.
>       That is meaning.
>
>    

With XSLT it's a little less likely that anyone would do anything very 
useful with a stylesheet other than execute it, but it's certainly a 
theoretical possibility.

Michael Kay
Saxonica