The files EXPAND.PA and KP52EX.PA are part of the 'expansion package' for
LDF-V5D.  EXPAND is the fundamental part: it allows up to 48 additional
functions and eight 'User' commands.  All the internal routines normally
called by new functions and commands are available in EXPAND.  Typically
the user who wishes to expand the interpreter beyond its Field 1 boundar-
ies starts with EXPAND and adds a lot to it.  The expansion routines can
go in any field above 2, however most users put them in Field 3.  This has
the effect of pushing up the start of the symbol table, patches for which
are included in EXPAND.PA.

KP52EX is an example of an 'expansion routine'.  It implements the KEYPAD
and PLOT commands in another field, thus freeing a little space in Field 1
for something simple (like an A/D function, for example).  This file has
not been upgraded for VT100 support, hence anyone interested in actually
using this code with a VT100 should compare the code with that in VTPLOT.