Hi Raphael,
the /SCWM/TMAPSTLOC is used for mapping for the ERP storage location to an EWM availability group (that will later be used for stock type determination). Therefor the entries are similar and the number of entries is usually low.
As I do no 100% understand your requierement I'm not sure if this table is right for you.
I understand that you want to determine the production plant. May be the inbound delivery could be a better source. Via partners you should be able to identify the source.
Best regards,
Christian