xml-dev - Re: Structured attributes

[Philip Nye <philipnye@freenet.co.uk>]

"Henry S. Thompson" wrote:
> 
> ...we all know the comparison between elements and attributes as
> they stand:
> 
> Elements      Attributes
> ordered       unordered
> non-unique    unique
> structured    unstructured
> 
> There are a lot of contexts in which the first two properties of
> attributes are desireable, but the third is a serious constraint.

Henry,

I cannot quite follow your axioms here. Taking bare XML syntax without
reference to any particular schema language, I would rephrase the table
thus.

              Elements            Attributes
Ordered?      schema dependent    schema dependent
Uniqueness?   schema dependent    schema dependent
structured?   schema dependent    No

Am I wrong? Is there anything in the syntax apart from DTDs which forces
unique unordered attributes? Is there any reason why elements must be
ordered? (apart from problems with arbitrarily complex content models
and the & operator - problems which might rear their heads anyway if
attributes bacame structured).

Your proposal for adding structure to attributes, turns attributes into
elements anyway (at the syntax level) so why bother with attributes at
all?

Philip

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