Clockwise angle in degrees (more rarely in radians) between the high side of the tool and pad 1 azimuth. Not defined for a well section that is horizontal. For holes deviated up to approximately 30º the relationship RB = P1AZ – hole azimuth should hold.
RIDER, M., 1996. The Geological Interpretation of Well Logs, Whittles Publishing, Caithness, p280.