When there is a reference to the system field *PAGE in a PRTFIL Header/Footer, 2E generates the DDS keyword PAGNBR.
An automatic facility that generates a page number on each page for you up to 9,999.
There is no reference to this in the actual program for the PRTFIL.
If you want to add and control your own page number then you will need to drop *PAGE field and add your own function field to the Device
Then in the program you can use EXCUSRSRC to define and manipulate the field as you wish.