156 STL (Standard Tessellation Language) ASCII Stereolithography File (ASCII) Model STL is a 3D modelling file format created by 3D Systems. An STL file is a triangular representation of a 3-dimensional surface geometry. The surface is tessellated or broken down logically into a series of small triangles (facets). Each facet is described by a perpendicular direction and three points representing the vertices (corners) of the triangle. These data are used by a slicing algorithm to determine the cross sections of the 3-dimensional shape to be built by the fabricator. Text 1 Digital Preservation Department / The National Archives 02 Aug 2005 16 Mar 2012 x-fmt/108 PUID stl File extension 596 STL <optional blank>solid + … + “facet normal” + … + “outer loop” + … + vertex 1 Absolute from BOF 0 (73|2073)6F6C696420*6661636574206E6F726D616C20{0-200}6F75746572206C6F6F70{0-20}76657274657820