fastran's singualr axis

autofly

HOw to set the axis boundary conditions at the fastran cfd software. in the given B.C. TYPE. there is not the axis B.C on the general B.C. menu. BuT in the demo validation examples of the attached PDF files, the grid around HYPERSONIC missile include the axis, so it must be able to deal with the axis b.c. I try to define the aixs b.c as symmetry b.c .it run well .but i can't certain it. who can give me some explatation and suggest. thanks in advance