DocBook for authoring Technical Requirements, Specifications?

[William Reilly <william@reilly2001.info>]

Greetings.

Searching Google, OASIS, and "Requirements" community sites hasn't yet shown 
me whether there are XML vocabularies generally in use for creating system 
requirements and technical specifications documents.

DocBook occurred to me, despite its having been designed to "doc"ument a 
system more than specify one.

Any "SpecBook" or "ReqBook" out there?

Or is going the MS-Word or OpenOffice .DOC template route the only way these 
days? (or Rational ReqPro, LiveSpecs, and similar expensive commercial 
products)

Perhaps it's that the overhead of authoring in a markup language is seen as 
detrimental to the shorter life of these "upstream" documents, as compared to 
downstream documentation efforts, which ought to endure long after a system 
is built and in use.

Many thanks for suggestions, comments.
William Reilly
Somerville, Massachusetts, U.S.A.
william@reilly2001.info