Documenting Schemas  

The issue of documenting schemas—or any machine readable language—goes beyond simple additions of comments. Thereal challengeistocreateschemasthat arereadablebothdirectlybylookingat their sourcecodeandbydocumentation extraction tools.

van der Vlist, Eric. O'Reilly and Associates (2001). Articles>Information Design>XML>Documentation

RELAX NG: Complex Patterns  

One of the key differentiations between compositors and simple patterns is that compositors are patterns that don’t directly map to any individual element withinthe schema. I emphasize this distinction because it can be easy to forget when focusing on a schema instead of the instance document.

van der Vlist, Eric. O'Reilly and Associates (2003). Articles>Information Design>XML