An editor's save changes bytes nobody edited (fixed point through floats)

Symptoms

A file saved from the decoded view differs from the original in fields that were not edited, usually in the last bits of positions far from the origin.

Cause

The game stores positions as 16.16 fixed point; the viewer holds them as 32-bit floats, which keep 24 bits. POD's tracks reach about 2,000 units, which needs 27 bits plus a sign, so a float cannot hold every stored value (inferred from the ranges; the editor was written to avoid it).

What to do

Never write fields back from the float view. Record each field's offset when reading; an edit adds a rounded fixed-point delta to the stored integer and writes it at that offset. Untouched fields keep their bytes. Test that a save with no edits is the original on every file.