An angular measure type for recording rotation measurements about an axis. Extends the standard plane angle measure with an attribute to identify the feature about which rotation occurred (e.g., bedding plane, fault plane, joint). This is used in structural geology and rock mechanics to document rotation of blocks or features, particularly in areas of tectonic deformation, landslides, or toppling failures.

The type of geological or structural feature about which rotation occurred (e.g., bedding plane, joint, fault, foliation). This identifies the axis or plane of rotation and provides geological context for the measurement.