Full Idea
In addition to the sense and reference of term, there is the 'computational' role. The name '2' has a sense (successor of 1) and a reference (the number 2). But the word 'two' has little computational power, Roman 'II' is better, and '2' is a marvel.
Gist of Idea
A term can have not only a sense and a reference, but also a 'computational role'
Source
James Robert Brown (Philosophy of Mathematics [1999], Ch. 6)
Book Reference
Brown,James Robert: 'Philosophy of Mathematics' [Routledge 2002], p.92
A Reaction
Very interesting, and the point might transfer to natural languages. Synonymous terms carry with them not just different expressive powers, but the capacity to play different roles (e.g. slang and formal terms, gob and mouth).