[XSLT 2.0] Data types for a Basic XSLT processor

I do not understand the rationale for the numeric datatypes permitted
for a basic processor. Could someone explain, please?

My thoughts are on the following lines:

The programmer ought to have the choice between accuracry and speed of
operation.

The former is represented by xs:decimal and xs:integer.
The latter by - well what?
I would have said xs:int and xs:float.
-- 
Colin Paul Adams
Preston Lancashire