You can determine whether the production version is selected manually or automatically when the order is opened. You set this up in the order type dependent parameters (Production version indicator).
The default is automatic selection. If you have chosen manual selection, you are prompted to select a production version when you open an order.
The setting of the Production version indicator is only evaluated if there is an entry in the Selection method field in the MRP3 tab page of the material master, that envisages selection by production version (selection by production version, selection only by production version).
How the production version is selcted, depends on the Production version
indicator that is maintained in Customizing for production orders by choosing Master data -> Order ->
Define order type dependent parameters .