public VariableReference bindVariable(StructuredQName qName) throws XPathException {
XSLVariableDeclaration xslVariableDeclaration = element.bindVariable(qName);
VariableReference var = (xslVariableDeclaration.isGlobal()
? new VariableReference()
: new LocalVariableReference());
xslVariableDeclaration.registerReference(var);
return var;
}