Re: [xml-dev] XML spec and XSD

[Jirka Kosek <jirka@kosek.cz>]

Mukul Gandhi wrote:

> My point was, that XSD and DTD (and also XML) are "W3C" specs. RelaxNG
> is an OASIS specification. I haven't seen W3C specs, recommendating
> users to use OASIS specs, *and* mentioning these statements in W3C
> specs themselves. Or do we have any instances of W3C specs, where W3C
> recommends users to use certain OASIS specs. This more so doesn't
> happen if W3C and OASIS develop competing languages. But I don't see
> XSD and RelaxNG as competing to each other.

If you will look at newer document formats specified by W3C they use
RELAX NG as a primaty schema language -- simply because in RELAX NG it
is easier to express necessary constraints then in W3C XML Schema (and
sometimes RELAX NG is the only grammar based schema language in which
constraints can be specied). Examples are MathML 3, SVG 1.2, XHTML 2.0
was also using RELAX NG.

If you look at validator.nu and Relaxed -- the two validators who have
much better error coverage then validator.w3.org for web pages, you will
find that they are based on RELAX NG schemas + (Schematron or special
check written in procedural code).

> Looking at the XML spec, the XML spec seems to convey that DTD is an
> inseparable part of XML definition. But if DTD is inseparable from
> XML, why cannot XML spec say that XSD can be used for validation as
> well (since XSD is a better XML validation technology, and is also
> developed by W3C)?

Standard are books of code not textbooks.

> I even think, that a future XML spec other than referring to XSD as an
> alternative XML validation technology with DTDs, should also provide
> means to embed XML Schema's inline the XML documents, as we do with
> DTDs.

There is already spec which provides this capability -- XML Namespaces.

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