A midnight deadline is often specified for applications, submissions, or contests in the Wikimedia community. This leads to numerous problems: What time zone is that for? Is it the beginning of the day or the end of a day? Is Daylight Saving Time a factor?
To avoid the ambiguity of such a deadline, it is considered best practice to make the deadline for 23:59 Anywhere on Earth (AoE) as the last day to file. This means anyone who submits locally on the last day in their geography is accepted.
Anywhere on Earth (AoE) is an international standard that is equivalent to UTC−12:00 hour. Daylight Saving Time (DST) is not relevant to this use case.
Projects and events are encouraged to use this as a best practice.