How to access MB_DOCUMENT_BADI table parameters.

Hi experts,

i'm trying to getting access to the data structures XMKPF XMSEG of the MB_DOCUMENT_BADI but i can't reference them by typing XMKPF-FIELD or XMSEG-FIELD it returns an error : "they isn't header tables" , how can i get access to these structures to validate some fields when the user saves a record on the MIGO tcode ?.

Tnxs a lot.