The STL format
Provides import and export of ASCII and binary STL files.
Format
STL is a file format native to the stereolithography CAD software created by 3D Systems. This file format is it is widely used for rapid prototyping and computer-aided manufacturing. STL files describe only the surface geometry of a three dimensional object without any representation of color, texture or other common CAD model attributes. The STL format specifies both ASCII and binary representations. Binary files are more common, since they are more compact. Both formats are non-proprietary and can be studied in detail e.g. at http://en.wikipedia.org/wiki/STL_(file_format).
Import a STL format file