Leap Concrete/Conspan Load Rating

I am using Leap Concrete/Conspan to do a load rating for prestressed concrete beams that have multiple spans but not continuous at the piers.  When I go into the Rating Parameters to the "Rating Options," and click on "All," it will give me load ratings for the longitudinal reinforcement (values vary from about 0.97 to 3.50), among other things.  However, I do not have any longitudinal reinforcing steel in the beam, only prestressing strands.  What is this "longitudinal reinforcement" option checking?