Daddy? Where Do Schemas Come From? Some Facts of Life for Schema Users
http://2006.xmlconference.org/programme/presentations/143.html

Sperberg-McQueen, C.M.
XML 2006
2006

Abstract:

The rules for finding schema components when validating a document using W3C's XML Schema 1.0 are widely misunderstood. This presentation will the rules for constructing a schema and describe the reasoning behind the design.