Ah... If you go into LBWE and choose the maintaing of the structure you can see that the extract structure MC03UM0 is based on the R/3 structure MCMSEG. This structure is based on the table MSEG, so I would suggest you should check the datasource against the entries of MSEG....
I don't think so... You can check the values only manually with transation RSA3Extract data and check it against the original data... Isn't a suffiscient way but it seems that SAP ...
