SAP table T8J8B (Stepped Rate Overhead Rules (JVA))
SAP table T8J8B has 3 primary key fields being MANDT,BUKRS,STEPRULE.
If you're only analyzing data from a single SAP instance you may omit field MANT in your relationships as it will we the same across the entire dataset. On the other hand, if you're combining data from multiple SAP instances you need to take MANDT into account.