Re: Are we losing out because of grammars?

[Rick Jelliffe <ricko@allette.com.au>]

From: Charles Reitzel <creitzel@mediaone.net>

>1) Simple things should be simple.  Although subjective, I think grammars
>win easily by this measure.

Aha, have we found someone who thinks XML Schemas is simple?  :-)

This week I have been looking at XML Schemas for SVG's use of XLink. Their
innocuous usage is very hard to figure out in CR XML Schemas (I think
something will work itself out) but trivial in DTDs and XML Schemas: so I
think it is important not to say that what is even simple in one
grammar-based system is simple in all.

> To my mind, such validation is not a schema language requirement, per se.

So to be able say "element x must have a child y" is a requirement but to be
able say "document z must have a element y" is not?   Why?

Or what about "the twelfth <month> in a <year> has 31 <days>"?  Is that a
schema requirement? That can be expressed in some grammar languages but not
others.

What about "an xlink:locator element should not appear as the top-level
element of a document"?  Is that a schema requirement?

Cheers
Rick Jelliffe