useful in Scheme to have abstractions on *data* as well as functions? Got a useful example?

[chris at seberino.org]

It is clear from SICP book that abstractions are useful to create bigger
functions from combining smaller functions.

 e.g. (define (fred x) (* (+ x 4) 10))

Is there an example where abstractions on *data* are useful as well?
In other words, when would it ever be useful to give a *name* to some
combination of data such as...

      (1 8 10 11 (5 6) (9 (10 4))) ???

Abstractions aren't *JUST* for functions are they???

cs