So, back up. Opener starts 2C and Responder bids 2D. Opener now bids 2H. If Responder has a 5-card major, he can show it immediately, in case Opener has 4-3 or 3-4 in the majors and a long minor, or a 5+ hearts and unbalanced hand, with three spades.
We save space, however, to give room.
With 5-5 or better in the majors, a major fit exists, one way or another. So, Responder bids 3D. Whatever Opener's options, he has a major of at least 4-card length. Opener simply sets trumps, and cuebidding follows. Maybe Responder bids his stiff, though.
With five cards in hearts, and 0-4 spades, Responder bids 3C. When Opener has the hearts-and-unbalanced hands, we have a fit. With the heart-minor canape, we have a fit. With the spade-minor canape and a 3-card heart fragment, we have a fit. In all three circumstances, and to be consistent with what follows, Opener bids 3D to artificially agree hearts, and cuebidding follows, or Opener could blast 4C or 4D to show maybe the heart-minor canape and a "picture bid." With no heart fit, Opener has spades and a longer minor with 0-2 hearts; in this event, he flags his long minor (3H = clubs, 3S = diamonds).
Why the flags? Consistency. For, if Responder has five spades (and 0-4 hearts), he bids 2NT. If Opener has the heart-minor canape with 0-2 hearts, he flags the minor (3H for clubs, 3S for diamonds). With the unbalanced hands with 5+ hearts (and 0-2 spades), Opener bids his longer minor (3C or 3D), but 3C might be bid with 2623 (Responder bids 3D to express interest in clubs, Opener bidding 3S to confirm real clubs). With spade support, Opener bids 3NT or something at the 4-level (maybe canape completions).
Responder calso has two other main rejects of the relay -- 3H or 3S to show a stiff in the other major, two or three cards in the bid major, and 4+ in each minor, with promising values. The reason why this shows shortness in the other major is to allow Opener to focus hearts after the 3H call:
2H!-3H(short spades, 2-3 hearts)
3S(I have five hearts)...
(or 3NT = hearts agreed)
So, in summary so far:
Opener bids 2C
Responder bids 2D
Opener bids 2H (hearts and unbalanced, OR four-card major with 5+ minor)
1. 2S waiting
2. 2NT with 5 spades, 0-4 hearts
3. 3C with 5 hearts, 0-4 spades
4. 3D with 5-5 majors
5. 3H with 0-1 spades, 2-3 hearts, 4+ in each minor, values
6. 3S with 0-1 hearts, 2-3 spades, 4+ in each minor, values
If Responder bids 2S waiting, Opener bids:
a. 2NT = 4-card major with longher minor
b. 3C or 3D = natural with 5+ hearts
c. 3H = six hearts
d. 3S = 6H/4S
e. 3NT = 5H/4S
If Opener bids 2NT, Responder bids:
I. 3C asking
II. 3D with 4-4 majors
If Responder bids 3C asking, opener bids:
i. 3D with diamonds
ii. 3H with hearts and longer clubs
iii. 3S with spades and longer clubs