If you intent to create a 2D-mesh for the cfd-code duns or isaac you have to watch out that all surfaces are created in the same order. That means that all surfaces must be defined clockwise or counter-clockwise. For isaac they have to be counter-clockwise if you look in z direction. The block-structure can be detected only in this case. You can check the mesh by simply mesh it with linear shell-elements and display them. All elements must be either dark or illuminated. A later ``qflp'' or ``flip'' command will not cure wrong oriented surfaces since it only changes the ``sign'' in their definition and not the basic edge sequence, which is necessary here. The results of a calculation can be opened by specifying the parameter (-duns2d -duns3d -isaac2d -isaac3d) and the filenmae without any extention(cgx -isaac2d RAE2822). See also ''Program Parameters'', ''mesh'', ''send''. Watch also the airfoil-example in the distrib.