S Woodside wrote:

Why not write your schema in Relax NG (RNG) and convert it to W3C XML Schema (WXS) using Trang ? All the work is already done for you ... RNG is MUCH easier to write and read.
http://www.thaiopensource.com/relaxng/trang.html
simon

the schema I am generating imports an master schema and extends the subsitution groups defined therein (like OO inheritance/poymorphism -. very nice). Despite all talk about other schema languages being equivalent or superior to XML Schema, I have found none that really support this.