XPath and XPointer

Does XPath actually have provisions for creating new axes? The AxisName
production is not extensible. It seems to me that XPointer should only
extend XPath in ways that have been forseen in XPath.

If other axes are legal, is it legal for those axes to return object
types (e.g. "range") that are not in the set of XPath data types:

 * node-set (an unordered collection of nodes without duplicates) 
 * boolean (true or false) 
 * number (a floating-point number) 
 * string (a sequence of UCS characters) 

Thanks,

 Paul Prescod