To match a string of any length (including the empty string) that is comprised exclusively of lower-case ASCII letters : pattern « XML Schema « XML Tutorial

<xs:pattern value="[a-z]*" />


Below is an example of element content that matches the above pattern:

<example>qwertyuiop</example>


Describing structured numeric strings like US Social Security Numbers (SSNs): 

<xs:pattern value="\d{3}-\d{2}-\d{4}" />


Allow only the ten ASCII digits, using this character class expression


<xs:pattern value="[0-9]{3}-[0-9]{2}-[0-9]{4}" />

3.79.pattern
	3.79.1.	Pattern syntax
	3.79.2.	list of atoms that match a single character
	3.79.3.	Character classes
	3.79.4.	Unicode character classes
	3.79.5.	User-defined character classes
	3.79.6.	Meta Characters
	3.79.7.	These three characters should be used with caution:
	3.79.8.	A character class expression is simply a character group, enclosed in square brackets
	3.79.9.	Any single normal character will match only that character
	3.79.10.	Special regex characters (-[]) cannot be used for the single normal character form of the character range.
	3.79.11.	Any ASCII letter: adding a second character range to the character group expression
	3.79.12.	To match a string of any length (including the empty string) that is comprised exclusively of lower-case ASCII letters
	3.79.13.	Specifying a Pattern for a Simple Type
	3.79.14.	Pattern for time
	3.79.15.	You can use patterns to offer choices for an element's content.
	3.79.16.	Getting rid of leading zeros
	3.79.17.	Use quantifiers to limit the number of leading zeros-for instance
	3.79.18.	Merge our three patterns into one
	3.79.19.	pattern Constrains the lexical space to literals that must match a defined pattern
	3.79.20.	A phone number
	3.79.21.	Define a pattern that can be used for zip codes
	3.79.22.	pattern: USA_SSN datatype