Re: POSIX locales and Roman Numerals

From: Markus Kuhn (
Date: Fri Jun 25 1999 - 14:39:48 EDT

"Alain" wrote on 1999-06-25 15:22 UTC:
> I'm puzzled... Who dumped Roman numerals even in Europe?

The primary culprit was an Italian of the name Leonardo Pisano, who
called himself Filius Bonaccii, today probably more well known as
Leonardo Fibonacci. He summarized in 1202 A.D. the complete knowledge on
algebra and arithmetic in his book "Liber abaci". This book then caused
the decimal system and the many simplifications that it brought to
become widely used in Western Europe. With the decimal system came also
the concept of the number zero, for which there exists no equivalent in
the Roman notation of numbers.

The European/ISO time notation (midnight at the start of the day = 00:00)
made elegant use of this invention of the digit zero, while people in
the US still follow the Roman number tradition and have to start the day
with "hour number XII ante meridian". The problems of the US time notation
are obvious and numerous:

  - It is longer than the normal 24h notation ("12:00 A.M." versus "00:00").

  - It takes somewhat more time/effort for humans to compare two times
    in 12h notation.

  - It is not clear, how 00:00, 12:00 and 24:00 are represented.
    Even encyclopedias and style manuals contain contradicting
    descriptions and a common quick fix seems to be to avoid
    "12:00 a.m./p.m." altogether and write "noon", "midnight", or
    "12:01 a.m./p.m." instead, although the word "midnight" still
    does not distinguish between 00:00 and 24:00 (midnight at the
    start or end of a given date).

  - It makes people occasionally believe that the next day starts at the
    overflow from "12:59 a.m." to "1:00 a.m.", which is sometimes a
    problem not only when people try to program the timer of VCRs
    shortly after midnight.

  - It is not easily comparable with a string compare operation.

  - It is not immediately clear for the unaware, whether the time
    between "12:00 a.m./p.m." and "1:00 a.m./p.m." starts at 00:00
    or at 12:00, i.e. the English 12h notation is more difficult to

It is a shame that people actually invest effort to represent the time
of the day in such a baroque way even in the computer age in the US. If
you read the data sheet for the battery-backed clock chip on your PC
mother board, you will notice that is contains even special hardware
support for presenting the time in am/pm format to the CPU, which then
has to use additional code to convert it back into a more straight
forward notation. It is mind boggling, to what trouble US engineers go
to preserve these bizarre habits appentently without ever thinking were
they came from or whether they are practical. Exactly the same happens
with the metric system, A4 paper, and all the other improvements and
modernized conventions that the rest of the world has in the mean time
happily adopted. Welcome in the 21st century.

Some aspects of i18n have nothing to do with culture. They are just sad.


P.S.: If you want to learn more about a neat idea burried in an exercise
found on pages 123-124 of Fibonacci's Liber abaci, and if you don't mind
reading my German high-school thesis, then please be invited to have a
look at

Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at,  WWW: <>

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