The US Departmet of Defense has adopted the AEC CADD Standard, based upon the National CAD Standard. The AEC Standard actually references the NCS, so the two are very closly ties together. Here's the website, where you can download the entire manual for FREE!
http://tsc.wes.army.mil/products/standards/aec/intro.asp
This CAD standard is very complete and contains charts on all of the layering standards, colors, lineweights, etc. Of course it's DWG/DGN based, but it might help you ArchiCAD'rs..... (See? We Revit users can be helpful, too!)
Scott Davis
Autodesk, Inc.
On March 5, 2007 I joined Autodesk, Inc. as a Technical Specialist. Respectfully, I will no longer be actively participating in the Archicad-Talk fourms. Thank you for always allowing me to be a part of your community.