NVDL, (Namespace-based Validation Dispatching Language)

I've spent some time with Schematron recently and quite enjoyed it. I wanted to document one of the Schematron stylesheets and looked around for a namespace mix that would allow me to create an XWEB document. I should have guessed! Norm was there first. Guessing, he came from \TeX ideas and applied them in XML. His stylesheets, still in use in the docbook build, provides what's needed. He tells me it's more generally applicable, which is impressive, to say the least. Being greedy, I thought about validating my file.xweb. That took me back to DSDL, in particular to NVDL. That... in theory (and it's probably pretty good theory, though I haven't proven it yet) enables me to validate mixed namespace XML instances without much fuss. Using dumb copying ideas, I generated an NVDL schema (script? - I'm unsure what it should be called) and a few sub-schemas which together validated one of Norm's files. I was impressed. Then I started to look round for more documentation on NVDL. It is thin on the ground. I used to think James C's writing was terse. I've now found an author who is closer to maths than English for spec writing. ISO has a copy. Yet again I agree it's written for implementors. No I don't like that (as a user). Google failed me until Jirka pointed me to Sourceforge and jnvdl. At last I have something to read! Thanks Petr.

I have a feeling that this is going to be one subtle puppy. Three implementations is good though. jnvdl from Petr, onvdl from oXygen, and (possibly short term), linked from this message. this seems to be the mono source of the latter implementation.

If I get my head round it, I'll put a document up on my website.

XSLT 2.0

Onother weekend job for me. I've extracted much of the syntax from XSLT 2.0, XPath and the F+O functions. They are available as four pages of ten point PDF at my xslt 2 pages. It attempts to do for XSLT 2 what Mulberrytech did for XSLT 1.0 with their quick reference card.