Enumerated complex types

Hello,

I was wondering if the use case of enumerated complex types had ever 
come up in this list. I did a quick search and couldn't find anything.

Here is what I mean:

Let's say I want to define a list of error codes, each having a possible 
value, an associated severity level and description, which I have 
specified in the form of a table, and I want to return in an XML message 
this information in the form of a <Status> aggregate containing a 
<StatusCode> element, <Severity> element and <Desc> element. This is a 
realistic use case you can find in industry standards such as IFX and ACORD.

One solution would be to use co-constraint rules: if StatusCode is '100' 
then Severity must be 'Error' and Desc must be 'General Error', but that 
sounds quite complicated and it wouldn't help the manual edition of a 
schema-compliant XML document.

The alternative solution I'm thinking about would be something similar 
to the xs:restriction and xs:enumeration used in simpleTypes, but with a 
value that would essentially be an XML document fragment.

I see several advantages to this representation:

    * It could be leveraged to accelerate the manual edition of XML
      instances of an XML Schema through code completion: I select one
      of the enumerations in a drop-down list, just like today XML
      editors allow me to select an enumerated value from a drop-down list.
    * It is easier than co-constraint representation for business people
      to understand and edit.
    * It might be easier for type checkers to deal with (intuition).

Let me know what you think and sorry if this has already been discussed.

Guillaume