Below is an overview of all file formats of TetGen.

.node	input/output	a list of nodes
.poly	input	a piecewise linear complex
.smesh	input/output	a simple piecewise linear complex
.ele	input/output	a list of tetrahedra
.face	input/output	a list of triangular faces
.edge	output	a list of boundary edges
.vol	input	a list of maximum volumes
.var	input	a list of variant constraints for facets/segments
.neigh	output	a list of neighbors

Click on each link to see the description of that file format. Here are some examples files which are very simple but good for illustration.

In addition, TetGen supports (reads and writes) the following public polyhedral file formats.

.off	input/output	Geomview's polyhedral file format
.ply	input	Polyhedral file format
.stl	input	Stereolithography format
.mesh	input/output	Medit's surface mesh file format

A graphic program, TetView, created specificially for viewing the input and output files of TetGen is also available. It has many features for viewing and analysing piecewise linear complexes and meshes. Furthermore, it outputs high quality frame dump of the screen images in encapsulated postscript format (.eps). The executable version is available for free.