I've got an Excel package that is the start of a project to automate the development of such a thing as far as possible. It's actually been used in anger on a couple of projects too. It starts with a sheet which lets you look at each loop and identify what indication, control, alarm functions are needed, and also the associated field devices, turns this into an instrument index and then a shopping list, and has space for cable connection schedules to be developed from this as well.
If you want a play, contact me off-line (bmdurdle(AT)clear.net.nz) and I'll e-mail you the master sheet with instructions.
I started writing it over 10 years ago in Smartware but that, like a lot of good packages from the mid-80's, seems to have gone to that great big software clearing house in the sky ...
I developed a product called the Fisher Rosemount Instrument Information System, which was used to provide revision control on electronic data sheets for instrumentation. 80+ sites were installed worldwide. Product discontinued due to lack of funding by original developer (Kenonic Controls Ltd.). It was used by big companies - Saudi Aramco was one, BP, Amoco, Syncrude Canada.
What kind of open source product did you have in mind?
We are also concentrating on that area and have something avaliable for CERN. Our approach focus on very efficient access to objects that were red from the database.
Also we are looking into time based information (like a database type of CVS thing).
Please let us know if you think that we could merge efforts.