PO Message Output

Dear All,

In the SPRO purchase order output message we add the prog which have the requested format designed by ABAP but while creating PO i have to assign the message type and then it the PO print view is apperaing in requested format. i want that message to be as a constant. so everytime we create PO the PO output message should be same if we want to change then we could but i want one message always as a default.

reagrds,