const, TYPE, VAR

     The following are globally declared in the NestTTT5 unit:

     CONST
        MAX_LEVELS = 10;
        MENUSTRLENGTH = 40;
        DONTCLEAR    = 0;
        REFRESHTOPIC = 1;
        REFRESHMENU  = 2;
        CLEARCURRENT = 3;
        CLEARALL     = 4;
        UNDEFINED    = 99;

       VAR
         NEST_USERHOOK : POINTER;   {VER 4.0}
         NEST_DESPATCHER: POINTER;  {VER 4.0}
         N_FATAL : BOOLEAN;
         N_ERROR : INTEGER;
         NTTT    : N_DISPLAY;

     Max_levels - this byte constant is the maximum number of menus that
     can be nested, i.e. displayed on the screen at one time. The value of
     10 is somewhat arbitrary and can be modified to any reasonable value.

     MenuStrLength - this byte constant is the maximum number of characters
     in a topic description. The value of 40 is somewhat arbitrary and can
     be modified to any reasonable value.

     The unit includes five refresh code constants that have the following
     meaning:

     DontClear - return to the menu and do not refresh the screen.

     RefreshTopic - redisplay the highlighted topic. This is often used
     when the despatcher procedure has modified the topic description.

     RefreshMenu - redisplay the entire menu. Use this option when more
     than one of the current menu's topic descriptions have been modified.

     ClearCurrent - remove the current menu and display the prior level
     menu.

     ClearAll - this is the code to terminate menu execution. All the menus
     are removed and the screen is restored to its original state.