How Sub Ledger Journal Entries Transfer works in Dynamics AX?

Sub Ledger Journal Entries Transfer
Subledger journal entries transfer means that additional performance optimization and summarization rules can be defined for the transfer of subledger journal entries to General ledger. The transfer process can be defined so that it occurs synchronously or asynchronously. During the transfer process, a user has the option to summarize the subledger journal entries for similar source documents to reduce the amount of data in General ledger. User also has the option to select particular source documents like Free text invoices, Purchase Orders, Purchase requisitions, Vendor Invoices etc. to reduce the amount of data in General ledger.
The path of the form is General ledger > Setup > General ledger parameters

There are two rule type on which Batch transfer rules can be applied:
Document
Company

By selecting Company rule type then it applies to all the source documents that are linked to the particular legal entity and by selecting Document then it applies to the specific source documents.

There are three types of transfer mode:
Scheduled batch
Synchronous
Asynchronous

Scheduled batch:
It will run within the batch jobs with a scheduled interval: E.g. every 10 minutes or once a day or perhaps once a week.
Synchronous:
It will execute from within the posting process started by the user itself. For example: when an invoice is posted, the posting logic will also execute posting the subledger lines. This is from within the post task the user started.
Ascynchronous:
Posting process will only create the document and subledger lines from the client process. Then after it is finished the server thread will pick it up as soon as possible.
The asynchronous method is a thread on the server which will pick up immediately after creating the subledger entries.
Advantage: Client machine will be earlier ready and the user can continue with other tasks.

Summarized entries can only be applied for Scheduled batch and Asynchronous batch transfer mode because in synchronous transfer mode, transactions cannot be posted in summary or detail whereas in Scheduled batch and Asynchronous, transactions can be posted in summary or detail.