Sign Inversion in LIS-DataSources

Hi guys,

does anyone know how LIS-DataSources do Sign-Inversions on Key Figures?

I am guessing that this is done based on document types and/ or categories somehow.

For instance a SD billing document of the type "credit note"has positive values in its ERP-datatable VBRP in the specfific value fields (i. e. subtotal1).

The datasource provides data records for that same billing document with negative values in field subtotal.

So somewhere in the coding of the datasource there has to be a logic that does the sign inversion.

My Problem is, that I have to do the same within a generic datasource.

Any hints are very much appreciated.

Best regards,

Tobias