Solution : https://service.sap.com/sap/support/notes/323541 (SAP Service marketplace login required)
Key words :
additional key words sapmkauf, attached source code corrections, order type belonging, double-clicking select, object class, master data, internal orders, transaction ko02, field selection, pressed enter
Related Notes :
| 506607 | INFO: Field sel. for int. order master data in order type |
| 79653 | 'Object class' field can be changed via F4 |