The program begins working its way along the design group until it gets to the end of a segment. A segment end occurs at the start of the design group, at the end of the design group, and wherever a full, partial or lateral flange restraint has been applied to the critical flange. Thus the current design segment is the portion of the design group that extends from the current critical flange restraint location back to the end of the previous design segment (or start of the design group).
For each station in the segment, the program does a cross section capacity check using the forces and moments which occur simultaneously at that point. It also does various member checks for the segment as a whole using all possible combinations of maximum forces and moments that occur anywhere in the segment.