Over what time period is 'Today' measured for the Game Center leaderboard?

Does anyone know over what time period the Game Center leaderboards measure 'Today'? In other words, if I play a game and get a high score for 'Today开发者_如何转开发', at what time does that score no longer appear in the 'Today' category?

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12:00 AM PTZ <== that's where apple is

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"Today" in Apple's Game Center really means the most relevant score in the past 24 hours (even though this can easily span more than one actual day).

Here's a reference to the time scope documentation for GKLeaderboardTimeScopeToday:

Each player is restricted to scores recorded in the past 24 hours.

http://developer.apple.com/library/ios/#DOCUMENTATION/GameKit/Reference/GKLeaderboard_Ref/Reference/Reference.html#//apple_ref/c/econst/GKLeaderboardTimeScopeToday