6 and 8-node finite elements are defined in text file syntax as first - nodes, and then nodes in the centers of particular finite element edges.
A different principle holds during presentation of results for 6 and 8-node finite elements. The nodes creating an element are listed in the following order: node, node in element center, node, and so on.
It is recommended to use 3 and 4-node planar elements. If 6 and 8-node planar elements are used for mesh generation the following options may not work correctly.