Over 3C or 3H opener will usually relay; over 3S, sometimes. The
relay suit is the next higher. Opener shows his shortness in steps,
in the order C, D, OM. Over 3C-3D, with the big balanced or semi-
balanced hand opener bids the cheaper minor-suit control. Non-relay
bids are asking bids, again in steps. That is, over 3C, 3H is an
asking bid in clubs. Responses are in steps, showing control of the
suit asked: 1st step shows no control, 2nd shows Q or XX, 3rd shows
K or X, 4th shows ace.
Over 3D responder shows shortness: 3H = doubleton club, 3S = doubleton
diamond, 3NT = doubleton heart, 4C = non-minimum 4x3, 4D and 4H show
singleton club and diamond respectively and a hand too strong to
splinter, and 4S shows a minimum 4x3. (Bergen's splinters are limited
to 12 HCP at most.)
After all of this, cuebids and kickback follow.
Source: Don Varvel (email@example.com)