Layers, again (was Re: fixing (just) namespaces and validation)

Rick Jelliffe ricko at
Sat Sep 11 08:14:23 BST 1999

 From: Simon St.Laurent <simonstl at

>No, you don't have the choice of applying _validation_ at whatever
>you like - currently, you have the choice of applying it or not
applying it
>during the parser.

It seems a bit strange to say on the one hand that "XML is too
monolithic" and at the same time that namespaces should not be a
separate layer and should be folded into the base spec. Which is not to
say that it is an impossible view.

However, I don't understand the quoted paragraph: who has the choice of
validation?  The recipient of a document can choose validation only by
installing a validating parser; the generator of a document can only
choose validation the same way!  The instructions needed for a document
to *instruct* a system as to what kind of validity may be required are
missing from any XML spec: the standalone declaration is advisory.

Without such a mechanism, validity cannot be part of schemata: a
document cannot assert that it should be valid (according to a DTD or
any other schematic) before it is used. I think this is a hole that
should be plugged.

Rick Jelliffe

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