TX30000 and Cashbook transactions

Hi,

For normal PM, RM transactions the DOCNUMBR field in the TX30000 links back
to the RM & PM tables on either documnr or vchrnmbr.

For all cashbook (bank management) transactions a document no gets created
in the TX30000 that does not seem to link back to any other table. I need to
be able to link back to the source table of all VAT transactions to get the
original GL entries created by those documents.

Please can you tell me if there is indeed some way to link these Cashbook
VAT entries back to either a Cashbook table, RM, GL, PM e.t.c table based on
this document no in the TX30000 table?

Thank you

Neil