[docbook] numbered para element for program language statutes/clauses orlegalese?

[Doug du Boulay <ddb at owari dot msl dot titech dot ac dot jp>]

I was wondering what the (DocBook and XSL) options are for having 
sequentially numbered/labelled paragraphs such as legal statutes or 
clauses where the labelling remains sequential, continuous across multiple 
section?

Basically I am looking to emulate something like:
    http://www.iucr.org/iucr-top/cif/spec/version1.1/cifsemantics.html
(hmmm. seems to be off air at the moment)

where most paragraphs are numbered, but for instance, the second etc. para 
elements of a certain point aren't. None of the numbered paragraphs have 
titles.

Presumably each numbered para should have an explicitly defined unique
(non-numeric?) ID for cross-referencing between relevant clauses. 

Have other folk needed anything like this, and if so, what did you do?
Is there a common @role attribute id customization anywhere?

Thanks
Doug