Once any major suit is raised from 1 to 2 (declaring suit agreement), a new suit is a game try. It suggests a suit JTx or better that would benefit from fitting honors (Qxx or better). One may bid game, sign off, or make another game try.
When this treatment is used, other bids change their meanings.
-
2NT shows a balanced hand
-
3 of the trump suit is preemptive/blocking (1-2-3-stop)