Hi
My understanging, the Pre-DME file is created when the payroll is in exit mode. we can do the simulation for PRe-dme, Posting to finance and third pary remittance before we exit the payroll.
so I think the reason SAP recommend to exit the payroll first before creating Pre-DME, because if there is some employees in the matchcode W. the system will show a warning message....in this case the payroll should run another time.
but if you create the Pre-DME file before exiting the payroll, you can send the file to the banque incomplte, and some employees will not receive their payment because the payroll was not run for them
Rachid