ERRORS

     There are a number of conditions that can generate Toolkit errors.
     Whenever an error occurs, the global byte variable N_Error is updated
     with the error number (listed below).

     The Toolkit can treat errors in one of two ways. If the global boolean
     variable N_Fatal is set to true (default) then any error will be
     fatal, i.e. an error message is displayed and the program halts. If
     N_Fatal is set to false then the N_error variable is set but the
     program continues (as best it can!) - be sure to check N_error after
     every menu call if N_Fatal is false. It is recommended that the
     N_fatal flag be set to true until your programs are fully tested and
     debugged.

     The list of error codes for N_errors are:

     0    NO ERROR
     1    NO MEMORY TO ADD A TOPIC
     2    NO MEMORY TO SAVE THE SCREEN IMAGE
     3    NO ACTIVE PICKS IN MENU
     4    NOT USED
     5    MENUS NESTED TOO DEEP, MODIFY MAX_LEVELS
     6    TOPIC NOT DEFINED - CANNOT MODIFY IT!
     7    NO DESPATCHER PROCEDURE ASSIGNED