Plywood thicknesses are available in:
Moisture Resistant plywood, also known as commercial plywood, with the IS 303 specification number. It's recommended for surfaces that don't get wet, like lofts and wardrobes.
Boiling Water Resistant plywood, with the IS 303 specification number. It's superior to MR plywood but inferior to BWP plywood.
Boiling Water Proof plywood, also known as marine plywood, with the IS 710 specification number. It's the strongest plywood and is recommended for surfaces that can get wet, like bathroom units and kitchen units.