MB01 Printer determination by Userexit? T685B-PRKEY='E' ?

Hi all,

in MM customizing for Output types for Goods receipt (Tcd. M706), I discovered the field VN_T685B-PRKEY - Print parameter. Within SAP Rel. ECC 6.0, the value help for this field offers value 'E' for 'User-Exit'.

I am very much interested in using this option, because my customer wants the printer to be determined via the Purchasing group of the Goods receipt's underlying Purchase order.

Does anybody have information about how and where to implement this USerexit? SAP Docu doesn't mention this value E at all

Thanks in advance!

Klaus