Forcing or Not Forcing 12

Forcing or Not Forcing 12

Question:

Is South's final bid Forcing or Non-Forcing and why?

  West    North    East    South  
 1NTPass2clubs icon
Pass2diamonds iconPass3hearts icon

Answer:

Forcing. Depending on your agreements, this either shows five spades and four hearts (Smolen), or five hearts and four spades (natural). New suits on the 3-level after Stayman are always forcing.