Complex sentence: Transition (A and B) class to Form 6 (A-I), But classes of Form 4 and above were named with 4S1,4S2 and so on while the art classes remained as Form 4 (A-D) since 2007.
Split into simpler sentences: Transition (A and B) class to Form 6 (A-I). However, classes of Form 4 and above were named with 4S1,4S2 and so on while the art classes remained as Form 4 (A-D) since 2007.