Double-tap or two single-taps?

Question

What is the time limit for two taps to be considered a double-tap, on the iPhone OS?

// Edit: Why is this important?

In order to handle single-tap and double-tap

Answer 1

In the Apple provided example of the iPhone Application Programming Guide: Event Handling (mentioned by user Italy) a delay of 0.3 is used:

[self performSelector:@selector(handleSingleTap:) withObject:touchLoc afterDelay:0.3];