[tz] Maritime time zones

Alan Mintz Alan_Mintz+TZ_IANA at Earthlink.net
Thu May 24 21:18:58 UTC 2012

At 2012-05-24 06:50, Tim Thornton wrote:
>Maritime time zones are well defined - basically every 15 degrees but with
>the odd wiggle in them - see
>They are identified by a letter, as shown in the above diagram.
>They were created in the 1920s and I think are virtually unchanged since

The 15-degree/hour concept is the basis for all time zones, not just the 
nautical ones. On land, note that they meander all over the place - this 
seems to attempt represent the correct boundaries on land as well.

>Note that the nautical date line is different from the international date

Where (as of 2010)?

>Also, it uses GMT (i.e. UT1, not UTC) - I'm not sure if the tz database can

Actually, it says "Universal Time". I don't see mention of GMT anywhere. 
It's likely that reality is UTC, since that's what everyone syncs to.

>So they could be included in the TZ database if people feel this is good -
>it would make the database more complete. Perhaps in a separate file, as
>they are not associated with any of the continents?

I don't know how useful they are any more. They used to be used as an 
improved abbreviated time format in two-way radio applications (primarily 
morse-code, some voice). It's probably still used in military applications. 
I occasionally still hear "Zulu" used for UTC. AFAICT, it can be easily 
added to the existing table for the "standard" time zones to which it 
applies, though it could be even easier just to add it to wikipedia (while 
I'm doing other work on times there).

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