Which table does PO notification report extract data from

Dear support,

I found in Purchase Order Notification report, sometimes the data is extracted from table PO_HEADERS_ALL and PO_LINES_ALL, sometimes the data is from table PO_HEADERS_DRAFT_ALL and PO_LINES_DRAFT_ALL.

Would you please let me know in which situation the data is extracted from PO_HEADERS_ALL and PO_LINES_ALL, and in which situation the report uses table PO_HEADERS_DRAFT_ALL and PO_LINES_DRAFT_ALL?

And, when and what will trigger the data transferred/copies from PO_HEADERS_DRAFT_ALL and PO_LINES_DRAFT_ALL to PO_HEADERS_ALL and PO_LINES_ALL?