---
title: xArbitraryZVertical
framework: coremotion
role: symbol
role_heading: Type Property
path: coremotion/cmattitudereferenceframe/xarbitraryzvertical
---

# xArbitraryZVertical

A reference frame where the Z axis is vertical and the X axis points in an arbitrary direction in the horizontal plane.

## Declaration

```swift
static var xArbitraryZVertical: CMAttitudeReferenceFrame { get }
```

## Mentioned in

Getting processed device-motion data

## Discussion

Discussion When you start the device-motion service, Core Motion sets the frame of reference to the device’s initial orientation. You might use this option when you don’t need to know the device’s attitude relative to true or magnetic north, and only track rotational changes over time. This option uses fewer sensors to determine the device attitude, and is more power efficient than the xArbitraryCorrectedZVertical option. tip: Save the first reported attitude value, and compare it to new values to determine changes since the start of the service.

## See Also

### Getting the reference frames

- [xArbitraryCorrectedZVertical](coremotion/cmattitudereferenceframe/xarbitrarycorrectedzvertical.md)
- [xMagneticNorthZVertical](coremotion/cmattitudereferenceframe/xmagneticnorthzvertical.md)
- [xTrueNorthZVertical](coremotion/cmattitudereferenceframe/xtruenorthzvertical.md)