The attributes, which are typically floating-point values of physical quantities (such as mass or conductivity) associated with the nodes of a finite element mesh, are copied unchanged to the output mesh. If -s, -q, or -a is selected, each new Steiner point added to the mesh will have quantities assigned to it by interpolation.
If the fourth entry of the first line is `1', the last column of the remainder of the file is assumed to contain boundary markers. Boundary markers are used to identify boundary points and points resting on PSLG segments. The .node file produced by Triangle will contain boundary markers in the last column unless they are suppressed by the -B switch.