diff --git a/index.bs b/index.bs index 4f20fc9..2a18115 100644 --- a/index.bs +++ b/index.bs @@ -200,7 +200,7 @@ Note: This choice of angles follows mathematical convention, but means that alph A device's orientation is always relative to another coordinate system, whose choice influences the kind of information that the orientation conveys as well as the source of the orientation data. -Relative orientation is measured with an accelerometer and a gyroscope, and the reference coordinate system is arbitrary. Consequently, the orientation data provides information about changes relative to the initial position of the device. +Relative device orientation is measured with an accelerometer and a gyroscope, and the reference coordinate system is arbitrary. Consequently, the orientation data provides information about changes relative to the initial position of the device. Note: In native platform terms, this is similar to a relative OrientationSensor on Windows, a game rotation vector sensor on Android, or the xArbitraryZVertical option for Core Motion. @@ -215,7 +215,7 @@ This specification expresses a device's motion in space by measuring its acceler Acceleration is the rate of change of velocity of a device with respect to time. Is is expressed in meters per second squared (m/s2). -Linear acceleration represents the device's acceleration rate without the contribution of the gravity force. When the device is laying flat on a table, its linear acceleration is 0 m/s2. +Linear device acceleration represents the device's acceleration rate without the contribution of the gravity force. When the device is laying flat on a table, its linear acceleration is 0 m/s2. When the acceleration includes gravity, its value includes the effect of gravity and represents proper acceleration ([[PROPERACCELERATION]]). When the device is in free-fall, the acceleration is 0 m/s2. This is less useful in many applications but is provided as a means of providing best-effort support by implementations that are unable to provide linear acceleration (due, for example, to the lack of a gyroscope).