FreeEOS is a stable software library for calculating an equation of state for conditions in stellar interiors. The latest stable version of this library source code, FreeEOS-1.6.0, has been released on 2005-09-01. The principal change to the software for this version of FreeEOS is the physical constants have been upgraded from CODATA 1986 to CODATA 2002. For more details see the announcement at http://freeeos.sourceforge.net/announcement-1.6.0.html . This stable release is the one I will support from now on and also gives the most accurate benchmark against the next stable release so this is the version you want until that next stable release.