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

Mark Davis ☕️ mark at
Fri Jan 22 01:57:48 CST 2016

I think it really depends on context. I think the following, for example,
refer to the same time, the instant between Tuesday and Wednesday.

   - Wednesday, I was wide awake from midnight to 5am.
   - Tuesday, the party lasted from 7pm to midnight.

The context of a range makes it clear what was meant.

I'm ok with holding back on using midnight, except when

   1. there is a word for midnight in the locale that (predominantly) means
   the start of the day (00:00).
   2. in time intervals (where the context is then clear enough). However,
   see below.

Normally, date-time software views time-periods as half-open intervals. For
example, the first hour of a day is from 00:00 to 00:59:59.9..., a day is
from 00:00 to 23:59:59.9999..., a year is until Dec 31, 23:59:59.9999...,
and so on.

#2 is connected with a separate ticket which is to allow for the
time-of-day to be *formatted* as being 24:00 or after. The primary use case
for that is to allow time intervals (eg for opening hours) to span
midnight, which are used in some countries, such as:

Wednesday 18:00 – 25:00

However, it could also allow for the use of a term "midnight" for 24:00,
where that is the most natural expression.



On Fri, Jan 22, 2016 at 7:40 AM, 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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