21.2 Defining Commands

A Lisp function becomes a command when its body contains, at top level, a form that calls the special form interactive. This form does nothing when actually executed, but its presence serves as a flag to indicate that interactive calling is permitted. Its argument controls the reading of arguments for an interactive call.

21.2.1 Using interactive		General rules for interactive.
21.2.2 Code Characters for interactive		The standard letter-codes for reading arguments in various ways.
21.2.3 Examples of Using interactive		Examples of how to read interactive arguments.