i-Lab Guide To: XML Schema

What Is It ?	XML Schema are a successor to the DTD (Document Type Definition) for defining the structure and content of XML data. XML Schema present a number of advantages over DTDs :- they are themselves valid XML files (i.e. they can be translated using XSLT for example to provide documentation or sample data) they provide many more facilities for data validation The main disadvantage of XML schema is that they are much more verbose than DTDs, making tool-support obligatory for all but the simplest of definitions.

Namespace
xmlns:xs	http://www.w3.org/2001/XMLSchema
Data Types
boolean	0, 1, true, false
date	CCYY-MM-DD
time	hh:mm:ss
dateTime	CCYY-MM-DDThh:mm:ss (ISO 8601)
float, double
decimal, integer...	long, int, short & byte

base64binary	65 characters { Alphanumerics, equals, plus and forward slash } plus whitespace
hexBinary	16 characters { Numbers and upper-case letters } plus whitespace
string	Free text except that special characters need to be escaped
normalisedString	As string, except without line feeds, carriage returns or tabs
token	As normalisedString, except without leading/trailing, or groups of more than one, spaces
NMTOKEN	Alphanumerics plus period, colon, underscore and hyphen (no spaces)
NMTOKENS	One or NMTOKENs separated by single spaces
Name	As nmtoken, except must start with a letter, underscore or colon
NCName	As Name except without colons
Commenting
XML 1.0 Comments	<!-- Read by parser but lost with XSLT -->
xs:annotation elements	with xs:documentation and/or xs:appinfo children
Foreign Attributes	TBD
Character classes
[a-z]	Characters between a and z
[^a-z]	Characters not between a and z
\d	Digits
\D	Non digits
\w	Word characters
\W	Non word characters
Quantifiers
{n,m}	between n and m
{n}	exactly n
*	0 or more
+	1 or more
?	0 or 1 {0,1}