Indexing uses the 4th axis to rotate the part between machining operations so that the machining takes place on different planes of the part. In FeatureCAM each face of the part can be assigned to a separate Setup or features can be placed radially around the center of rotation by using only one Setup.
Parts whose features can be accessed by rotating around a single axis are candidates for 4th-axis wrapping.
Note: You must have a CNC control that supports a 4th axis, and a rotary table or native 4th axis that can be controlled by the CNC machine to use indexing.