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# Predefined Time Interval Values

Time intervals between the absolute reference date and certain other dates.

## Topics

### Constants

[`let kCFAbsoluteTimeIntervalSince1970: CFTimeInterval`](/documentation/CoreFoundation/kCFAbsoluteTimeIntervalSince1970)

The time interval between 1 January 1970 and the reference date 1 January 2001 00:00:00 GMT.

[`let kCFAbsoluteTimeIntervalSince1904: CFTimeInterval`](/documentation/CoreFoundation/kCFAbsoluteTimeIntervalSince1904)

The time interval between 1 January 1904 and the reference date 1 January 2001 00:00:00 GMT.


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