(       Title:  [UNDEFINED] Bootstrap
         File:  undef.fs
      Version:  0.0.1
     Modifier:  David N. Williams
      License:  Public Domain?
Last revision:  March 5, 2002
Starting date:  March 3, 2002

This file defines [UNDEFINED] if it is not in the search order,
while affecting only transient memory if it is.  It may be
INCLUDED multiple times.

This was figured out by several people in comp.lang.forth before
us.  We've borrowed the file name from Bruce McFarling.  We
hope it becomes superfluous soon.
)

s" [UNDEFINED]" pad c! pad char+ pad c@ move 
pad find nip 0=
[IF]
: [UNDEFINED]  ( "name" -- flag )
(
Leave true if name is in the search order, else leave false.
)
  bl word find nip 0= ; immediate
[THEN]