Using "midnight" to mean the beginning of the day could be confusing

Philippe Verdy verdy_p at
Fri Jan 22 06:24:52 CST 2016

We have the same confusion in French, but it is disabiguated by the
context, when a sentence says that
- something starts on D day at midnight it means 00:00 at start of this D
day and not 24:00 at end of this D day
- something ends on D day at midnight it means 24:00 at end of this D day
and not 0000 at end of this D day
We need disambiguation when the context does not clearly state if this is a
start or end, i.e. an isolated timestamp. In such case we won't refer to
midnight ("minuit" in French) but 00:00 ("0 h" or "zéro heure" in French)
or 24:00 ("24 h" or vingt-quatre heures" in French). This is the same
situation as English.

In legal texts, the time of day is never used, only dates are specified and
they are inclusive (e.g. a new "commune" may be created on 1st January, the
legal text specifies the start day at it is implicitly at starting at
00:00; the same text specifies that older communes will end at the same
time; in most cases those legal texts are using starting dates that fall at
start of year or during a legal non-working or on monday when public
services are closed).

For contracts that need exact time working also on non-working days (e.g.
electronic transactions), timestamps are specified only numerically, never
by a sentence. For other dated contracts only dates are used inclusively so
that they inlcude at least the normal working time of signatories. When
there are organisations or people still working at midnight (shops,
restaurants...) the legal records contain only numeric timestamps (e.g.
billing tickets printed for their sales).

However "midnight" or "minuit" is definitely not a "day period", except in
fuzzy expressions like "This happened in the night between Sunday D and
Monday D+1, around mindight", where two dates are specified. If you wanted
to convert this to a numeric timestamp, it would be "D+1 00:00" or could be
a fuzzy date range such as "D 23:45 - D+1 00:15" specifying a rough
half-hour, or up to "D 23:00 - D+1 01:00" within a range of two hours. But
thjat "day period" is completely unspecified and left to contextual

2016-01-22 7:40 GMT+01:00 Martin J. Dürst <duerst at>:

> In my opinion, "could be confusing" is a gross understatement :-(. I just
> recently wanted to submit some abstracts to a conference where I spent
> about 10 minutes to figure out which end of a day the actual deadline was.
> While there may be conventions for such things in some communities, and
> CLDR has an ambition to follow them, it's highly confusing in the world
> wide context of the web. The less such things are made defaults, and the
> more exact terms are used (e.g. "midnight at the start of the day" or some
> such), the better.
> Regards,    Martin.
> On 2016/01/22 10:30, kz wrote:
>> Dear CLDR users,
>> I'm currently trying to implement in ICU the pattern characters b and B
>> for
>> datetime formatting, which involves the use of the word "midnight". See
>> .
>> Currently, according to the CLDR spec, the word "midnight" refers to 0:00,
>> i.e. the beginning of the day. However, after a conversation with my
>> colleagues, we feel that it's more natural for "midnight" to mean, at
>> least
>> in English, the end of the day. For example, "Wednesday midnight" would
>> refer to midnight of Wednesday-Thursday, not the midnight of
>> Tuesday-Wednesday. This could cause confusion to users.
>> In addition, other languages could have different problems with the use of
>> "midnight". For example, Chinese has two different words for "midnight
>> (beginning of day)" (*lingchen*) and "midnight (end of day)" (*wuye*).
>> As such, it'd probably be worth discussing to either (1) remove "midnight"
>> as a time period, (2) use a different word for "midnight", or (3) modify
>> spec to have "midnight" refer to the end of the day.
>> Any opinions?
>> Thanks
>> kz
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