Conformance in XML processors

Paul Prescod papresco at
Mon Jan 19 20:12:22 GMT 1998

David Megginson wrote:
> This doesn't really address the point, though.  If notations and data
> attributes are optional, then either support for embedding non-XML
> objects is also optional, or notations and data attributes are not the
> preferred way of embedding non-XML objects.  

The former is officially the case. After all, XML presents no other
mechanism for embedding non-XML objects. XLL does not yet exists, and
when it does, it will not be part of XML and is thus optional *by
definition*. So object embedding is definately optional.

OTOH, I am confident that the latter is also a factor (probably the
dominant factor) in some people's minds. I think that these features are
optional for all of the usual reasons features are made optional in any

 a) not everyone needs them
 b) some people say they do need them
 c) some people don't want to implement them
 d) we aren't confident that they are actually appropriate
 e) we aren't confident that they aren't.

Optionality gives the market a chance to decide. Of course XML's design
documents say it shouldn't have optional features, but IMHO that
criteria was shot when the distinction between well-formedness parsers
and validating parsers was invented.

 Paul Prescod
"You have the wrong number."
"Eh? Isn't that the Odeon?"
"No, this is the Great Theater of Life. Admission is free, but the 
taxation is mortal. You come when you can, and leave when you must. The 
show is continuous. Good-night." -- Robertson Davies, "The Cunning Man"

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