The  third  letter  of the three character channel code is  the  Orientation  Code,
which  provides  a  way  to  indicate  the  directionality  of  the  sensor measurement.

Z N E          Traditional (Vertical, North-South, East-West)
A B C          Triaxial (Along the edges of a cube turned up on a corner)
T R            For formed beams (Transverse, Radial)
1 2 3          Orthogonal components but non traditional orientations
U V W          Optional components
Dip/Azimuth:   Ground motion vector (reverse dip/azimuth if signal polarity  incorrect)
Signal Units:  M, M/S, M/S**2
Channel Flags: G