Here we would like to draw your attention to SKPR04 transaction code in SAP. As we know it is being used in the SAP BC-SRV (Basis Services / Communication Interfaces in Basis) component which is coming under BC module (BASIS).SKPR04 is a transaction code used for Maintaining Physical Document Class in SAP.
It comes under the package SDOK.
Transaction SKPR04 technical data table
|Purpose||Maintaining Physical Document Class|