Mexican 2D
An opening of 2D shows a balanced hand of 19-21 that may have a weak five card major.
Responder responds as follows:
0-4: pass with diamonds
5-6: 2H transfer to 2S over which responder may pass, or signoff in clubs or hearts 2S
transfer to 2NT
7+: 2H transfer to 2S, and the responder bids 2NT
7-9: 2S transfer to 2NT and then raise to 3NT showing balanced
10+: 2NT shows balanced
10+: 3x shows and a broken suit