Not pre-defined. Use values in original DA scenarios for guidance.
From a reply by James Sterret at the Decisive Action Group at Yahoo Groups:
"In the unit editor, in the lower left part of the window, you should
find three items: Basic Load, % Combat, and % Move.
Basic Load is the number of supply points required for the unit to be
at 100%, when it is at 100% RCP. For what follows, we'll be talking
of "adjusted Basic Load": a unit at 50% RCP only needs 50% of the
supply, so a unit whose Basic Load is 100 points will require 50
points when at 50% RCP.
% Combat is the % of the adjusted Basic Load burned every time the
unit is in combat. For ground combat, this is paid once for any
number of combats in a given turn. Arty and Air Defence pay once per
shot.
% Move is burned whenever the unit moves during a turn. 1km or 50km,
you still burn this."