Thank you for the input! Maybe I should clarify the file. This is an attempt to allow users or peoples access to their times zones. A date string, publication, scanned document, broadcast, etc. can contain the time zone. The tz database even includes these time zones. Some functions even require them to operate. Take the "conceptional problem" example. BRT/BRST are the abbreviations used for the Brazilia Time zone. The ":America/Sao_Paulo" file/location is defined as using the Brazilia Time rule "Brazil". Since this location follows Brazilia Time, it is given the abbreviation for that zone. It is not given a synonym for an offset from UTC. An example to clarify could be the recent offset change of Moscow Time zone from an offset of 3 to that of 4. MSK is the abbreviation for the regional time zone using the standard time definition of that zone. The ":Europe/Moscow" file assigns the offset used for that zone. The Moscow file can now safely be used to represent the "Moskva" rule that is the regional time zone, rather than creating a new zone. Since it is the only location that uses that time zone, one can assign ":Europe/Moscow" file as a link. The GMT example is an oddity case. GMT can stand both for a time, :Etc/GMT which I assume is the observatory location, and the English Isles regional time zone. I am also guessing that that was one of the reasons for UTC, so that an offset of 0 from the observatory would be taken as the offset rather the the time zone the English use. I also only compiled the times, as stated in the file, from 1970 to present. It is known that abbreviations are not unique. However, the list of conflicting zones, see near the end of file, is really small. Especially when Australia is assigned the local, state, country definitions and Indonesia. I will look farther into the assignment to see if any additional zones need creation. As it is clear that a present location might not actually be assigned to a time zone. I did not try to resolve conflicts, just link to the base location file that defined the actual time zone for a region. I did try to make sure to avoid not linking a file that didn't represent the regional time zone, but best to be safe. Thanks again, was helpful! Steve