Two years ago Ismael Olea (olea), Juan José Amor (jjamor) and David Escorial wrote the specifications of requisites for Donantonio, Donantonio it's an bibliographic system for automatic distribuited publication which will help us at es.tldp.org (called also LuCAS), now the implementation of this system is being discussed a lot in the lists of LuCAS...
The documents about the requisites were written in spanish two years ago, one month ago, we start to translate these documents to english:
Specifications of Requisites for Donantonio
Specifications of Requisites for Donantonio's cilents
Specifications of Requisites for Donantonio's user interface
Specifications of Requisites for Donantonio's server
All this documents are into LuCAS-Desarrollo, sorry at the moment we have this page only in spanish.
This system is required as a result of the increasing complication of the publication workings of documentation of free software.
The scope of the developed system reaches until the production of clients and servers for Donantonio, communication protocols between them and user interfaces; preferring the design of a system that can be embedded in other compatible applications so these can as well be compatible applications (clients, servers or interfaces) with Donantonio.
If you want to know more about of Donantonio, talk with us, or even participate in the developing of Donantonio, post a message to Lucas Desarrollo mail list (in this list as all the others of LuCAS you can talk in english freely ;-)).
Did you worked with Z39.50? It seems a semi abandoned so complex protocol. An early but failed Internet promise. But it's only my appreciation.
We think maybe the best aproach will be the W3C's semantic web, working with XML and RDF maybe using things like TAP.