What does the asterisk (*) mean on the shear stress results?
Segments with an asterisk (if any) form a trapezoidal cross-section, or part of one, of the type for which du Boys' equation for calculating mean (unfactored) shear stresses was specifically developed. In PC-Convey these Segments are together referred to as 'du Boys cross-sections'. Segments without an asterisk (which aren't part of a trapezoidal cross-section) have their mean shear stress calculated by applying du Boys' equation to the individual Segment.
du Boys cross-sections have their shear stresses calculated using a combination of the areas, wetted perimeters and hydraulic radii of the Segments making up the du Boys cross-section. Consequently, all Segments of a du Boys cross-section are given the same area, wetted perimeter and hydraulic radius. More information is provided in PC-Convey's Help - search for "PC-Convey Approach" and select the Shear Stress result.