what do KTOSL, VORGN and GLVOR mean

Hi Experts,

In BSEG, there is fields like KTOSL(Transaction Key),VORGN(Transaction Type for General Ledger), and in BKPF there is field GLVOR(Business Transaction), all of them seem to exlpain where the transaction happens. Can anyone explain this in more details,and how can I tell from the different values of these fields.

Best Regards

Chris