8.2 Forms of dspecs

A dspec is one of:

A symbol which is used as a dspec always names a function or a macro.

(setf foo) is a name for a setf function.

Note: nil is not a legal dspec, because it cannot have a function definition. Therefore when a dspec API returns nil , this should be interpreted in the usual way as "not found" or "not applicable".

8.2.1 Canonical dspecs

LispWorks User Guide - 11 Mar 2008