The standard for reporting Euler angles has changed in Motive 1.6 beta 1. In Motive it is possible to see the live update of a rigid body rotation by opening the Rigid Body pane and selecting the Real Time Info tab. The updated standards are found below.

Coordinate System: Right-Handed

Euler Angle Order: X ==> Y ==> Z

Euler Angle: Relative

Axis Assignment: X (Pitch), Y (Yaw), Z (Roll) 

The relative Euler angle order of XYZ means the rigid body is first rotated about the X axis, then the new Y axis and finally the new Z axis. Relative in this context means local coordinate changes due to the one rotation are considered in the sebsequent rotations.

The option to specify the Euler angle order when exporting data to a CSV file has been added in Motive 1.6. In prior versions the output was always global/absolute YZX. Global in this context means local coordinate changes due to the one rotation are not considered in the sebsequent rotations.

Sample code to convert quaternions to Euler angles is attached.