!TITLE Environmental
!KEY

'NOLC'      Establishes the "no lower-case"  convention  described  in  Section
            1.15.

'LC'        Establishes  the  "full  character  set"  convention  described  in
            Section 1.15. It is the default setting.

op(priority,type,name)
            Treat name name as an operator of  the  stated  type  and  priority
            (refer  to  Section  1.14.2).   name may also be a list of names in
            which case all are to be treated as operators of  the  stated  type
            and priority.

break       Causes  the  current  execution  to  be  interrupted  at  the  next
            interpreted procedure call.  Then the message "[ Break (level 1) ]"
            is displayed.  The interpreter is then ready  to  accept  input  as
            though  it  was  at  top  level.    If  another  call  of  break is
            encountered, it moves up to level 2, and so on.  To close the break
            and resume the execution which was suspended, type ^Y.    Execution
            will  be resumed at the procedure call where it had been suspended.
            Alternatively, the suspended execution can be  aborted  by  calling
            the evaluable predicate abort. Refer to Section 1.11.

abort       Aborts  the  current execution taking you back to top-level.  Refer
            to Section 1.11.

save(F)     The system saves the current state  of  the  system  into  file  F.
            Refer to Section 1.8.

prompt(Old,New)
            The sequence of characters (prompt) which indicates that the system
            is waiting for user input is represented as an atom, and matched to
            Old; the atom bound to New specifies the new prompt. In particular,
            the goal
                prompt(X,X)

            matches  the  current  prompt to X, without changing it.  Note that
            this only affects the  prompt  issued  for  read's  in  the  user's
            program;  it  will  not  change  the  propmts used by the system at
            top-level etc.