There are some special SD user exits in SAP which are so old that they aren’t even included in SMOD / CMOD; but which are still so popular today. These are;
- MV45AFZZ: Order-related stuff (VA0*)
MV50AFZ1: Delivery-related stuff (VL0*)
There are lots of things you can achieve in these programs. If you ever need to change something in the order / delivery flow logic, these programs are the first places to check.