[tz] Reason for 24:00

[Paul Eggert]

On 5/3/19 5:40 PM, Guy Harris wrote:
>> In a few cases (e.g., "24:00 the last Saturday in March") it's not
>> that easy to switch between 0 and 24, so we might use 24:00 even if
>> the original source uses a more circumlocutory form with 00:00.
> I.e., "24:00 the last Saturday in March" could be "00:00 the last Sunday in March" in some years and "00:00 the first day of April" in other years?
>
Yes, that's right.