As in .node files, the attributes are typically floating-point values of physical quantities (such as mass or conductivity) associated with the elements (triangles) of a finite element mesh. Because there is no simple mapping from input to output triangles, an attempt is made to interpolate attributes, which may result in a good deal of diffusion of attributes among nearby triangles as the triangulation is refined. Attributes do not diffuse across segments, so attributes used to identify segment-bounded regions remain intact.
In output .ele files, all triangles have three nodes each unless the -o2 switch is used, in which case subparametric quadratic elements with six nodes are generated. The fourth, fifth, and sixth nodes lie on the midpoints of the edges opposite the first, second, and third vertices.