hello guys, it's not an issue but i want to ask about another string on purchase order origin beside sale order number,

so i have SO that linked to PO, in the PO ususally field origin will has value SO number, but in my case it has another string other than SO number, like example,

i have SO with number: SO001, then confirm it, it will also create purchase order with origin or source document SO001, then i confirm the PO and validate the receipt (stock.picking) document, after all of things is finished on purchase order origin (source document) the value will be  SO001, OP001, i've checked the data of OP001 it was the order point (stock_warehouse_orderpoint) what the meaning of that, why odoo added another string on source document/origin in purchase order.. thanks