Restrictions

pattern

May be included in

(pattern), attribute, datatypeName param exceptPattern, element, list, mixed, pattern&pattern, pattern*, pattern+, pattern,pattern, pattern?, pattern|pattern

XML syntax equivalent

optional

Description

A pattern qualified as optional is optional. It must be matched zero or one times.

Example

 element died {text}?
 
 attribute see-also {list {token, token?, token?, token?}}