I’m starting with Ax 2012, and there are a lot of changes in the code. Almost all the tables of General Ledger are new in Dynamics AX 2012. It was difficult to understand how the ledger posts are now inserted and their relations. Below some important relations of GL that might help.
How a Ledger post (GeneralJournalEntry) is related with a General Journal Ledger.
How a General Journal Line is related with a Ledger post (GeneralJournalEntry)