SoIndexedFaceSet(3) on Linux
The text 0f055e6b4127, as Debian 8 (Jessie) shipped it.
The SoIndexedFaceSet class is used to handle generic indexed facesets. Faces are specified using the coordIndex field. Each face must be terminated by a negative (-1) index. Coordinates, normals, materials and texture coordinates from the current state (or from the vertexProperty node if set), can be indexed to create triangles, quads or polygons.