Hey there,

If you are referring to OBC reservation category of 3BRH in Karnataka, here is what 3BRH is.

OBC category students in Karnataka are divided into 1, 2A,2B,3A,3B categories.

Castes which belong to 3B category at Lingayaths, Vaishnavas, Bunts, Digambara Jains, Christians, Maratha, Kuruba etc. as given by the Backward Classes department of Government of Karnataka.

R stands for rural quota, students who have studied 1st to 10th in any non-urban area and H stands for Hyderabad-Karnataka quota, for students belonging to the Hyderabad-Karnataka region districts in the state.

Hope it helps.