Invalid transactions from 4.6c to ECC 6

Hello Experts,

We are upgrading our system from 4.6c to ECC6. I came across some transactions in 4.6c which have been replpaced by new transactions in ECC6. For eg VOPA is replaced by VOPAN, OVXG has been replaced by OVXGN etc but the old transaction will continue to be available and there are some transactions like VOTX which cannot be used in ECC6 and we will have to use VOTXN.

My questions is that after upgrade can we use old transaction (whichever is available in ECC6) or do we need to start using new transactions like VOPN and OVXGN?

Thanks,

Karan