The DEFINE command performs two functions:

    o  Assigns a value to a symbol (see subtopic "symbol"). For this
       function, the /FD or /PD qualifier can optionally be selected.

    o  Associates an SDA command with a terminal key (see /KEY).
       Several other qualifiers can be specified with /KEY.

    If the symbol or key is already defined, SDA replaces the old
    definition with the new one. Symbols and keys remain defined
    until you exit from SDA.