NavList:

---

I will quibble with your statement that "Then there are two special half-zone descriptors straddling the (nautical) dateline which both keep the same time, 12 hours from Greenwich, but one day apart and counted either as +12 or -12 depending on whether you're east or west of 180° longitude."

I don't think (for example) that 10 am July 2nd is the same time as 10 am July 3rd, does anybody else?

There are 25 standard zone descriptions, there are 25 letter designations, the whole alphabet minus only the "J". Let's see, the alphabet has 26 letters so if you take away one that leaves 25 letters for the standard time zone designations. The military suffixes all date time groups with the letter designation for the time being kept.

Why try to make something that is so simple, complicated with your description?

gl

(Now the country of Kiribati has added two "non-standard" zone descriptions, +13 and +14 so that they could keep time with their closer neighbors to their west.)

---

From: Frank Reed <FrankReed{at}HistoricalAtlas.com>
To: garylapook{at}pacbell.net
Sent: Saturday, December 14, 2013 2:27 PM
Subject: [NavList] Re: British Summer Time versus GMT

---

Gary, you wrote:
"there are 25, not 24 time zones. Zone Description + 1 though +12, that makes 12 so far. ZD -1 through -12, that's another 12 for a total of 24 so far."

Or perhaps you could say it this way: there are 25 zone descriptors. Of those, 23 are centered on 15° intervals of longitude starting with the band centered on the Prime Meridian, and each differs from its neighbor by one hour. Then there are two special half-zone descriptors straddling the (nautical) dateline which both keep the same time, 12 hours from Greenwich, but one day apart and counted either as +12 or -12 depending on whether you're east or west of 180° longitude.

I have felt for a long time that calling those zone descriptors "time zones" is probably misleading since there are many more than 24 (or 25) time zones in the world. Time zones are defined by governments, constrained in part by international agreements but primarily by international economic considerations. And as we all know, most time zones are only roughly aligned with the the 15° bands that underlie the zone descriptors, and roughly 18% of the world's population lives in time zones that are offset by half an hour (some integral number of hours plus 30 minutes from UTC). At minimum, the ideal time zones defined by zone descriptors should be specifically identified as "nautical time zones" or maybe better (since aviation uses them, too) "navigation time zones".

Just thinking about terminology...

-FER

----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------

: http://fer3.com/arc/m2.aspx?i=125738

: http://fer3.com/arc/m2.aspx?i=125750