How is the promise date defaulted automaticaly on the standard PO lines?

Oracle Applications : 12.2.8

A requisition is manually created for an item which is sourced from a blanket purchase agreement (Local BPA).

A standard PO is autocreated from the requisition.

At this stage the the promised date is enmpty on the PO line.

After the PO approval the promised date is fill in automatically. It seems to be the value defined in the item processed lead time.

Some notes explain that the value is defaulted from the agreed lead time define on the BPA. This field is not existing on the BPA.

Thanks in advance for your responses

Laurent