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# Clock Types

Clock types to use when configuring a timer.

## Topics

### Timer Options

[`kIOTimerClockUptimeRaw`](/documentation/DriverKit/kIOTimerClockUptimeRaw)

A clock type that increments monotonically, but does not increment when the system is asleep.

[`kIOTimerClockMonotonicRaw`](/documentation/DriverKit/kIOTimerClockMonotonicRaw)

A clock type that increments monotonically, and is unaffected by frequency or time adjustmets.

[`kIOTimerClockRealTime`](/documentation/DriverKit/kIOTimerClockRealTime)

The system’s real time, expressed as the amount of time since the Epoch.

[`kIOTimerClockWallTime`](/documentation/DriverKit/kIOTimerClockWallTime)

The system’s wall-clock time, expressed as the amount of time since the Epoch.

[`kIOTimerClockMachAbsoluteTime`](/documentation/DriverKit/kIOTimerClockMachAbsoluteTime)

A clock type representing the numer of ticks since the last reboot.

[`kIOTimerClockMachContinuousTime`](/documentation/DriverKit/kIOTimerClockMachContinuousTime)

A clock type representing the number of ticks since the last reboot, including when the computer is asleep.


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