Powder dictionary (pdCIF) version 1.0.1
The orientation of the \w (\q) and 2\q axis. Note that this axis is parallel to the specimen axial axis and perpendicular to the plane containing the incident and scattered beams. Thus for a horizontal orientation, scattering measurements are made in a plane perpendicular to the ground (the 2\q axis is parallel to the ground); for vertical orientation, scattering measurements are made in a plane parallel with the ground (the 2\q axis is perpendicular to the ground). `Both' is appropriate for experiments where measurements are made in both planes, for example using two-dimensional detectors.
The data value must be one of the following: