UG_IO SimSys CGNS 3D Grid File Type
A CGNS file contains a tria/quad face boundary surface grid and (optionally) a polyhedral element volume grid. See CGNS related documentation available at the CGNS web site for more information. The optional boundary reconnection, boundary condition, initial normal spacing, and boundary-layer thickness data are not supported. The internal format of CGNS type grid files is always binary and the UG_IO file format suffix will have no effect.