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Official German Time Web Site
by Markus Kuhn Sept. 29, 1998

Sept. 29, 1998

Brazil is not the only country with an official time zone web site. The German time zone web site by the Physikalisch-Technische Bundesanstalt contains DST information back to 1916. http://www.ptb.de/english/org/4/43/432/sumo.htm http://www.ptb.de/english/org/4/43/432/sumn.htm http://www.ptb.de/english/org/4/43/432/lega.htm Markus -- Markus G. Kuhn, Security Group, Computer Lab, Cambridge University, UK email: mkuhn at acm.org, home page: <http://www.cl.cam.ac.uk/~mgk25/>

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Names in time.h C extension
by Markus Kuhn Sept. 29, 1998

Sept. 29, 1998

Thanks for the many comments that I have received on the modernized <time.h> C API on http://www.cl.cam.ac.uk/~mgk25/c-time/ I'll try to respond to every comment individually, but there issue that I'd like to address first separately: the names of the new elements. Almost half of all comments that I received suggested that the current namespace use of struct xtime xtime_*() strfxtime() TIME_* be changed into something else. I received numerous alternative proposals, and the only common thing among them was that they were almost all different. Most of the criticism seemed to have been just a matter of taste and not based on technical superiority of the alternative. The individual proposals were: Paul Eggert: xtime -> stime (short for "standard time", no rationale given) Nathan Myers: xtime_format: "To plan or arrange in a specified form" xtime_compose: "To make or create by putting together parts or elements." xtime_resolve: "To separate (something) into constituent parts." Ken Pizzini: timex "There is an old tradition of language design that the language and its libraries strongly avoid using identifiers starting with the letter 'x' --- a desperate application writer can then blithely prepenend an 'x' to all its first-choice identifiers and be safe." John Hauser: xtime_sleep, xtime_pack, xtime_unpack Jake Knoppers: timex "I would recommend using the term 'timex'. It is a invented term, a.k.a. coined term or neoligism, to which can be attached the apprpriate definition as well as a note at the end of such defintion of ' Formerly known as xtime'. 'Time' as word is used with multiple meanings and its use can quickly become confusing and inadvertently may have unforeseen results. Having the x precede the _resolves the ambiguity resulting from the x after _ ." Ken Pizzini: lists moment, instant, beat, clock, chronos, tiempo, heure, favours chronos Antoine Leca: chronos is better than timex or xtime (without explanation) Ok, here my reply: How did I get to xtime? Well, the original type was called time_t and I wanted to stay as close as possible to the traditional naming scheme of the C API. So I removed the _t, because this is inappropriate for a struct name. Now I had a collision with time(). My new type was an "extended time", as it had extended range, extended resolution, and a leap second extention, so for me xtime for "extendted time type" was a very obvious and nearby choice. While reviewing the comments, I haven't found a convincing reason why any of the other name proposals are better. Many of them are definitely worse. Some points I want to mention are: - Since this type is both used for clock values and for time intervals, "time" seems to me a much more appropriate base term than anything based on "clock". The clock_* namespace is already reserved for POSIX.1. - The C API is completely based on the English language, introducing terms from other languages as Antoine proposed (chronos) would certainly break some tradition. - I have never run into the "old tradition" that Ken Pizzini mentioned of programming languages reserving x prefixes for application variables. Do you have a formal reference for this, especially for the C language. The thought that it is good practice to start all your application identifiers with "x" sounds quite bizarre to me. I am not too concerned about remote chances of name collisions with a small number of applications, as there are many simple tools out there to automatically replace identifiers in software. - the type can also be used for many things that can be described as non-standard times (TIME_MONOTONIC comes to mind), therefore I don't see at all the special appeal of stime (for "standard time"). - I was surprised that suggestions that I had expected were not made: mkxtime would follow closer the traditional naming (as I did with strfxtime), and the traditional C API does not use underscores inside words (I was more influenced by POSIX.1b "tradition" here) anyway. Nathan Myers' proposal xtime_format instead of strfxtime goes even in the opposite direction, imitating more OO-style naming conventions instead of preserving the old style. I'd leave these ambitions to those who write the Python, Ada, Java, and C++ bindings for these functions. - I used "delay" instead of "sleep" only because I feel that sleep implies that the process is suspended or that the processor is put into a sleep mode, while delay does not imply any such implementation detail. There is some tradition for sleep in the sleep and nanosleep POSIX system calls, but I felt that an OS-independent programming language should not imply implementation details such as sending the process into a sleep state. Therefore I considered the Ada and Turbo Pascal "delay" statements to be closer related and more appropriate as a source for the name. - xtime_pack and xtime_unpack has for me at least a very different connotation. For me, packing and unpacking sounds more like shuffling bits around into a more compact arrangement (analog to say Ada's "packed arrays"), and does not imply the application of time zone algorithms, etc. C programmers are familiar with mktime, so "make" seemed to me much more intuitive. The struct tm representation is referred to in the standard as a broken-down time format, therefore something based on breakup seemed to me the closest and most obvious choice for the name of the inverse function of "make". The existing practice of localtime() and gmtime() is not useful here, as the name there was completely based on the specific time zone. Frankly, I don't care at all about the names, I am much more interested in the functionality, but I am also not convinced why any of the alternative proposals I have seen so far is better than what we have at the moment. Therefore, I haven't changed anything here yet. The committee is probably anyway going to rediscuss this issue, no matter what we submit ... ;-) Markus -- Markus G. Kuhn, Security Group, Computer Lab, Cambridge University, UK email: mkuhn at acm.org, home page: <http://www.cl.cam.ac.uk/~mgk25/>

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RE: daylight-saving time in Egypt; problem with zic and `24:00'
by Olson, Arthur David (NCI) Sept. 29, 1998

Sept. 29, 1998

...unfortunately, `zic' does not let you enter the transition time `24:00', meaning midnight at the end of the day; it complains `invalid time of day'. `zic' should probably be enhanced to allow 24:00, as that is often what the rules actually say -- Egypt is an example of this.... Here's a proposed patch for zic.c to explicitly allow 24:00 (or 24:00:00); certainly if it gets used in data files such as "africa", a comment about the potential need for downloading a new time zone compiler might be placed near the scene of the crime. --ado *** 7.94/zic.c Mon Sep 28 23:11:25 1998 --- 7.95/zic.c Mon Sep 28 23:11:26 1998 *************** *** 1,6 **** #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)zic.c 7.94"; #endif /* !defined NOID */ #endif /* !defined lint */ --- 1,6 ---- #ifndef lint #ifndef NOID ! static char elsieid[] = "@(#)zic.c 7.95"; #endif /* !defined NOID */ #endif /* !defined lint */ *************** *** 901,909 **** error(errstring); return 0; } ! if (hh < 0 || hh >= HOURSPERDAY || mm < 0 || mm >= MINSPERHOUR || ! ss < 0 || ss > SECSPERMIN) { error(errstring); return 0; } --- 901,910 ---- error(errstring); return 0; } ! if ((hh < 0 || hh >= HOURSPERDAY || mm < 0 || mm >= MINSPERHOUR || ! ss < 0 || ss > SECSPERMIN) && ! !(hh == HOURSPERDAY && mm == 0 && ss == 0)) { error(errstring); return 0; }

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FW: Early DST for Chile?
by Olson, Arthur David (NCI) Sept. 29, 1998

Sept. 29, 1998

-----Original Message----- From: Ian Tragen [SMTP:ian@mirage1.u-net.com] Sent: Monday, September 28, 1998 3:38 PM To: 'tz' Subject: Early DST for Chile? I am informed that Chile changed to DST earlier than usual on Sunday 27th Sept. this year. Ian Tragen Mirage Audio Visual Media web site: http://www.mirage1.u-net.com =============================

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FW: Changes in zoneinfo
by Olson, Arthur David (NCI) Sept. 28, 1998

Sept. 28, 1998

-----Original Message----- From: Marcos Tadeu [SMTP:marcos@MicroLink.com.br] Sent: Sunday, September 27, 1998 12:11 PM To: tz(a)elsie.nci.nih.gov Subject: Changes in zoneinfo There are a DS for 1998(in)/1999(out). The Brazilian official page is http://pcdsh01.on.br/verao1.html This diff is generate from tzdata1998c.tar.gz file in slackware package. -------------------------------------------------------------- --- southamerica.orig Sat Feb 28 15:32:26 1998 +++ southamerica Sun Sep 27 13:07:49 1998 @@ -289,10 +289,15 @@ # Brazil Prepares for Papal Visit # </a>, # Church Net UK (1997-10-02). +# +# From Marcos Tadeu (1998-10-27): +# In 1998, the DS begin in October 11 and end in Feb 21, 1999. +# Brazilian official page: http://pcdsh01.on.br./verao1.html +# Rule Brazil 1997 only - Oct 6 0:00 1:00 D Rule Brazil 1998 only - Mar 1 0:00 0 S -Rule Brazil 1998 max - Oct Sun>=1 0:00 1:00 D -Rule Brazil 1999 max - Feb Sun>=11 0:00 0 S +Rule Brazil 1998 max - Oct Sun>=11 0:00 1:00 D +Rule Brazil 1999 max - Feb Sun>=17 0:00 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] # ----------------------------------------------------------

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FW: zoneinfo changes for Europe/Latvia
by Olson, Arthur David (NCI) Sept. 28, 1998

Sept. 28, 1998

-----Original Message----- From: alexander smishlajev [SMTP:als@turnhere.com] Sent: Monday, September 28, 1998 12:21 PM To: tz(a)elsie.nci.nih.gov Subject: zoneinfo changes for Europe/Latvia timezone info for Latvia is out of date. since 1997, switching to the "winter" time occurs at the end of October. please apply the following patch. thank you. alexander smishlajev <<europe.dif>>

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zoneinfo changes for Europe/Latvia
by alexander smishlajev Sept. 28, 1998

Sept. 28, 1998

timezone info for Latvia is out of date. since 1997, switching to the "winter" time occurs at the end of October. please apply the following patch. thank you. alexander smishlajev

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Changes in zoneinfo
by Marcos Tadeu Sept. 27, 1998

Sept. 27, 1998

There are a DS for 1998(in)/1999(out). The Brazilian official page is http://pcdsh01.on.br/verao1.html This diff is generate from tzdata1998c.tar.gz file in slackware package. -------------------------------------------------------------- --- southamerica.orig Sat Feb 28 15:32:26 1998 +++ southamerica Sun Sep 27 13:07:49 1998 @@ -289,10 +289,15 @@ # Brazil Prepares for Papal Visit # </a>, # Church Net UK (1997-10-02). +# +# From Marcos Tadeu (1998-10-27): +# In 1998, the DS begin in October 11 and end in Feb 21, 1999. +# Brazilian official page: http://pcdsh01.on.br./verao1.html +# Rule Brazil 1997 only - Oct 6 0:00 1:00 D Rule Brazil 1998 only - Mar 1 0:00 0 S -Rule Brazil 1998 max - Oct Sun>=1 0:00 1:00 D -Rule Brazil 1999 max - Feb Sun>=11 0:00 0 S +Rule Brazil 1998 max - Oct Sun>=11 0:00 1:00 D +Rule Brazil 1999 max - Feb Sun>=17 0:00 0 S # Zone NAME GMTOFF RULES FORMAT [UNTIL] # ----------------------------------------------------------

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FW: dls in Egypt (forwarded with permission)
by Olson, Arthur David (NCI) Sept. 25, 1998

Sept. 25, 1998

-----Original Message----- From: Rives McDow [SMTP:rmcdow@ibm.net] Sent: Thursday, September 24, 1998 9:56 AM To: Olson, Arthur David (NCI) Subject: dls in Egypt Dear Mr. Ols[o]n, In your recent updates, there were several items that I checked on from the IATA SSIM that I was not yet familiar with. I am still checking on most that I was not familiar with, but the item concerning Egypt I am not sure is outlined to reflect what actually happens there. Egypt changes their time at midnight between Thursday and Friday, so when you say the time changes the 4th Friday in September, are you meaning this? They change their time tonight (actually in about 5 minutes from when I send this message). As far as the 4th Friday as opposed to the last Friday, my sources have told me that it is the last Friday, but I am having them check more thoroughly to clear this up. Sincerely, Rives McDow

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FW: dls in Egypt
by Olson, Arthur David (NCI) Sept. 25, 1998

Sept. 25, 1998

-----Original Message----- From: Rives McDow [SMTP:rmcdow@ibm.net] Sent: Thursday, September 24, 1998 10:59 AM To: Olson, Arthur David (NCI) Subject: RE: dls in Egypt Dear Mr. Olson, It is fine with me for the questions to be forwarded; I sent it to you to avoid the traffic on the list if it is unnecessary. I thought the question I asked would be more pertinent to you and the way your code handled the data rather than a question seeking an answer about the data. I have regular contacts all over the world regarding local time information, and at some point will be running a full comparison with your data. I am interested in corresponding with someone who is familiar with the code using the data, and could possibly suggest a method of easily generating a listing of all the entries that are currently in use, along with the time zone and daylight savings information. With this in a tabulated type of format, I could run a full comparison with my data fairly easily. I am somewhat a beginner at using C, so it will most probably take me some time to write a program myself, and other things are more pressing. If you know of someone who is familiar with the code and data, please let me know. I use both the PC and the Mac, but prefer to use the Mac because of the ease in working with large files. Sincerely, Rives McDow

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