Other proposals
- XML Schema
- - developed by W3C Working Group (52 people!)
- - currently a Working Draft
- - divided into "Part 1: Structures" and "Part 2: Datatypes"
- XML-Data, DCD, SOX, and DDML
- - earlier proposals (W3C Notes)
- - predecessors of XML Schema
- Schematron
- - based on XPath tree patterns (instead of grammars)
Unique features of DSD:
- conditional constraints
- element IDs as non-terminals
- constraints on reference targets (points-to requirements)
- context-based default insertion
- simple redefinitions
- linear-time implementation
