I have one comment regarding the timezone file format. Why not use a few of 20 remaining bytes in tzh_reserved field for a magic number that would be unique to timezone data files? 4 bytes at the beginning of the file would be great, but if you're concerned about space then 2 bytes would do the job if selected carefully. Thanks. Dan -- Daniel Quinlan Member of the League for Programming Freedom quinlan@yggdrasil.com