File Level ID and Format Level ID - What is the Difference?

1) File Level ID is affected by the Creation date of the file itself.
The value is all numeric.
As you can see the second and third digits are the creation year.

For example, this file was created in 2007

File level identifier . . . . . . . . . . . :            1071113163354  
Creation date . . . . . . . . . . . . . . . :            11/13/07

And this file was created in 2008:
File level identifier . . . . . . . . . . . :            1081009095638    
Creation date . . . . . . . . . . . . . . . :            10/09/08        


File Level ID will change when the File creation date changes.

If you delete and recreate (or recompile) the file - even if you do not alter the file definition in any way such as by adding a field - the File ID will change.

The File Level ID will change just because the creation date has changed.

If you delete and restore a file the File Level ID will not change, because the restored version retains the original creation date.

This is also true of the Member ID; it behaves in the same way as the File ID.

The File Level ID is used in a few places, particularly save/restore.
- check this value if your access paths are rebuilding even though you did a ACCPTH(*YES)

2) The Format Level ID is a combination of hex values and is based on the actual file definition, such as the fields and what data types they are.

The only way to change the Format Level ID is by altering the structure of the file, such as adding a field.

If you delete and recreate a file from the same source code, the Format Level ID will not change.

If you delete and restore a file, the Format Level ID will not change.

It is this Format Level ID that programs check when they process a file.
If the Format Level ID is different from what it was when the program was first compiled, there will be a msgCPF4131 Level Check message.