15.20.5  VALUE 

You may define values for "Lexicals"
     DEFINE VALUE name=value [LOG=[ON|OFF]] [FAST[=ON|OFF]]
A  lexical  of the form V_name is give the value n If you specify LOG then
the value is typed on your terminal.  When FAST=ON the value is defined as
a  local  symbol  in  non  readable  form.   This  will  speeds  up symbol
definitions, but it has little effect on the symbol usage.  You should use
FAST  when you are repeatedly redefining symbols.  Non readable symbols do
not make sense for a SHOW VALUE command.  If you need speed, single letter 
names are the most efficient.
(Default:FAST=OFF)

                                  Example
     TD:DEFINE VALUE NORM=125.5
     TD:Y=Y TIMES V_NORM
Multiplies all data by 125.5.
     TD:DEFINE VALUE NORM=<100/V_SUM>
     TD:Y=Y TIMES V_NORM
Normalizes the data to SUM=100.

You  may  show all defined values with the SHOW VALUE command.  Individual
values may be shown by the SHOW LEXICAL command.  See:TOPDRAWER DATA