Posting Documents in General Ledger Accounting 
Use
If the balance of debits and credits in a document is zero, you can post the document. When you post the document, the system saves it and updates the G/L account balances.
Prerequisites
To check whether the balance of debits and credits is zero, choose Post. If this is not the case, the system does not post the document.
The system also checks whether the amount you are posting is less than or equal to the limit you are allowed according to tolerances defined by your system administrator.
Activities
Result
The system updates the document file and the G/L account balances.