.smesh files  Examples are found at here.  A .smesh file
represents a piecewise linear complex (PLC) as well as some
additional information. The .smesh file format is a simplified
version of the .poly format, that each facet only has exactly
one polygon, no holes, no segment and point inside. It is less
flexible than the .poly file format but is much simpler and
useful when the surface mesh is created by other programs.  Part
1 - node list  Part 2 - facet list  Part 3 - hole list  Part 4 -
region attributes list  Part 1 lists all the points, and is
identical to the format of .node files. <\# of points> may be
set to zero to indicate that the points are listed in a separate
.node file.  Part 2 lists all the facets. It is different from
the facet format of .poly file. Each facet in .smesh file only
consists of exactly one polygon. The corner list of each polygon
can be distributed over a number of lines. The optional boundary
marker of each facet is given at the end of the corner list. If
the boundary markers i