The angular positions and layout directions for labels on or around point feature symbols. This optional object specifies how to position a label following the direction of an angle. The angular position may be different for each feature (driven by one or more feature attributes) or constant for all features (specified by a fixed number).
The LabelDefinition.placement will still be used to indicate whether offset or centered positioning is required, but the exact position will be overridden by the angle calculated for the feature. Once the position has been determined, LabelDefinition.textLayout and LabelDefinition.textOrientation are used to specify the layout of the text at that position. Warning: If the expression attempts to use attributes which don't exist then no label will be produced. This is distinct from the attribute existing but having a null or empty value, which will be interpreted as a zero angle.