Customize SLA rules.

Summary: Need to customize SLA and can't create custom sources.

Content: We are trying to create in SLA a movement depending on the item category that is used on the PO and the geographical context of the transaction. Since is not possible to create a custom source to get this information through tables, we were looking at the possibilities that we have to retrieve what we need (until now, without success). We were trying to set a subledger Journal Entry Rule Set pointing to the Receiving Inspection accounting class since the movement is made when we need. However, we are unable to define a mapping set, a value set or getting