This is the base class for XML Schema elements that are related to identity constraint. 
 
Unique & operator=(const Unique &rhs)
Assignment operator. 
 
Unique(std::string *name, Annotation *ann=0, std::string *id=0)
Constructor. 
 
A class that models a XSD annotation element. 
 
It models the unique element in an XML Schema. 
 
IdentityConstraint * clone() const 
It clones the object.