Home  |   Site Map  |  Contacts  |  Forums        Quick links: Data Browser Download Data Coordinates Time Series Map Browser Orbits SCOUT CRTN Velocity Maps SIM SITe Locate Site
NASA/REASoN    |    CSRC    |    CRTN

A Comparison of Three Competing Meta-Languages

Features	DTD	XML SCHEMA	Schematron
Schema
Syntax in XML	No	Yes	Yes
Use of Namespaces	No	Yes	Yes
Include	No	Yes	No
Import	No	Yes	No
Datatype
Built in Types	10	37	0
User Defined Types	No	Yes	No
Domain Constraint	No	Yes	Yes
Null	No	Yes	No
Attribute
Default Value	Yes	Yes	No
choice	Yes	Yes	Yes
Optional vs. Required	Yes	Yes	Yes
Domain Constraint	Partial	Yes	Yes
Conditional Definition	No	No	Yes
Element
Default Value	No	Partial	No
Content Model	Yes	Yes	Yes
Ordered Sequence	Yes	Yes	Yes
Unordered Sequence	No	Yes	Yes
Choice	Yes	Yes	Yes
Min & Max Occurrence	Partial	Yes	Yes
Open Model	No	No	Yes
Conditional Definition	No	No	Yes
Conditional Definition	No	No	Yes
Element
Default Value	No	Partial	No
Content Model	Yes	Yes	Yes
Ordered Sequence	Yes	Yes	Yes
Unordered Sequence	No	Yes	Yes
Choice	Yes	Yes	Yes
Min & Max Occurrence	Partial	Yes	Yes
Open Model	No	No	Yes
Conditional Definition	No	No	Yes
Inheritance
Simple Type Extension	No	No	No
Simple Type Restriction	No	Yes	No
Complex Type Extension	No	Yes	No
Complex Type Restriction	No	Yes	No
Key or Uniqueness
Uniqueness for Attribute	Yes	Yes	Yes
Uniqueness for Non-Attribute	No	Yes	Yes
Key for Attribute	Unordered Sequence	No	Yes
Choice	Yes	Yes	Yes
Min & Max Occurrence	Partial	Yes	Yes
Open Model	No	No	Yes
Conditional Definition	No	No	Yes
Element
Default Value	No	Partial	No
Content Model	Yes	Yes	Yes
Ordered Sequence	Yes	Yes	Yes
Unordered Sequence	No	Yes	Yes
Choice	Yes	Yes	Yes
Min & Max Occurrence	Partial	Yes	Yes
Open Model	No	No	Yes
Conditional Definition	No	No	Yes
Inheritance
Simple Type Extension	No	No	No
Simple Type Restriction	No	Yes	No
Complex Type Extension	No	Yes	No
Complex Type Restriction	No	Yes	No
Key or Uniqueness
Uniqueness for Attribute	Yes	Yes	Yes
Uniqueness for Non-Attribute	No	Yes	Yes
Key for Attribute	No	Yes	Yes
Key for Non-Attribute	No	Yes	Yes
Foreign Key for Attribute	Partial	Yes	Yes
Foreign Key for Non-Attribute	No	Yes	No
Miscellaneous
Dynamic Constraint	No	No	Yes
Documentation	No	Yes	Yes
Embedded HTML	No	Yes	Partial