5
The entry period, with a time zone
Where a surprising number of disputes actually come from.
“Entries accepted from 12:00:00 a.m. on the 1st through 11:59:59 p.m. on the 30th, Eastern Time.” The seconds are not lawyerly showing off.
A promotion that says “midnight” without saying midnight where has created a genuine ambiguity worth several hours, and someone who entered during those hours will eventually want to know which side of the line they were on. A promotion that says “midnight on the 30th” has created a worse one, because midnight on the 30th is arguably the start of it.
So the good ones nail down a zone and a second. If you are entering near a deadline, that line tells you exactly how long you actually have — and it is often three hours more, or less, than you assumed.