actual shipment date on RMA order line

Hello All,

per the standard functionality, what does the actual shipment date on a RMA order line mean? because in the case of RMA there is no shipping to the customer involved (as in the case of the forward sales order), so what does that date mean? Does it mean the time it is interfaced to Receivables interface? or does it mean the time it is interfaced to inventory? or any other timestamp?

if the RMA's are not interfaced to inventory, then what would that actual shipment date on a sales order line mean?

Can some one please answer my question asap as i want to know what is the standard functionality.