All accounting documents are present in BKPF/BSEG.
The Invoice documents are present in RBKP/RSEG
When there is a tax amount entered against an document, those entries are added in BSET.
BKPF is the header table and BSEG is the item level table (?). It is a cluster table which has data from tables BSIK,BSAK, BSIS,BSAD, BSIS,BSAS.
Difference between BELNR and DOCNR
- BELNR : Document Number / BUZIE Line Item
- DOCNR : Account Document Number / DOCLN Line Item ( General ledger View )
The value in the fields of BELNR and DOCNR is the same. Just the item level details are changing as DOCNR/DOCLN gives you more line level detail.
In the FAGLFLEXA, we can find the GL related postings and in the above example, the total amount for line item 1 would be 30, when seen in BSEG table.
The t-code for checking this is FB03 -> Display -> <Entry View> will give the regular item details and when <General Ledger View> is set, it will give you further details view which are the DOCLNs.
When using datasource 0FI_GL_14, this has both BELNR/BUZEI and DOCNR/DOCLN and in general, DOCNR is mapped to 0AC_DOC_NR/AC_DOC_LN and BELNR/BUZEI to AC_DOC_NO/ITEM_NO.
Useful Links :
Asset Accounting Delta
BWOM_SETTING for datasources
Financial Account and Asset datasources