Check if Recompilation required:

You've just made a minor change to your display file. Now you must recompile all the programs that use it to avoid getting level check errors, right? Or do you?
The system assigns a unique level identifier to each record format when the display file is created. When you compile a program that uses the file, the compiler includes the format level identifiers in the compiled program.
Use the Display File Description (DSPFD) command to display the record format level identifiers for the file. Use the Display Program References (DSPPGMREF) command to display the record format level identifiers that were used when the program was created. If they are the same, you do not need to recompile the program to avoid a level check error.
Only changes to the following will affect the record format level identifier:
• Record format name
• Field names
• Length of the record format
• Number of fields in the record format
• Field attributes such as length and decimal positions
• The order of the fields in the record format
You can change field attributes such as highlight, underline, reverse image and colors without recompiling programs. Constants such as headings or labels can be added, changed or deleted. The screen locations of fields and constants can be changed as long as the order of the fields or length of the record format is not changed. This means that you can actually change the location and order of fields on the screen as long as you don't change their order in the DDS source member for the display file.