Subledger Events Creation

Hello,

I am trying to find out when the XLA events are exactly created during a receipt or invoice creation. I couldn't find much information besides that these are created when transactions are committed. Does that mean there are any standard business events which could be executing when a transactions are committed, if so which are these? Or is there something else that I am missing. In our case the receipts are created using a Standard Lockbox process. Any help is much appreciated.

Thanks,

Amar