PROJ.4 (or proj) is a library for performing conversions between cartographic projections. The library is based on the work of Gerald Evenden at the USGS, but is now an OSGeo project maintained by Frank Warmerdam. The library also ships with executables for performing these transformations from the command line. The first release of proj was developed by Gerald Evenden in the early 1980s as a Ratfor program. It was based on the General Cartographic Transformation Package or GCTP, which consisted of Fortran subroutines that could be used to project geographic data. The second release of proj from 1985 was rewritten in C to run on UNIX systems. The third release of proj from 1990, named PROJ.3, was expanded to support approximately 70 cartographic projections. Evenden further developed a fourth release in 1994, named PROJ.4, which is the current name of the software. The last version maintained by Evenden was 4.3, released on September 24, 1995. After over four years of inactivity, Frank Warmerdam became the new maintainer and released version 4.4 on March 21, 2000. As of May 2008, PROJ.4 become part of the MetaCRS project, a confederation of coordinate systems related projects under incubation with OSGeo. Source.