This directory contains a minimal version of BioNetGen, with only the portion that expands rule files.  The entry point for the program is BNG2.pl, which runs the perl scripts in the subdirectory Perl2.  The full version of BioNetGen is available at the website http://bionetgen.org/index.php/Main_Page.  That version includes simulators, graphical user interfaces, and other useful tools.  See the CREDITS.txt file for the BioNetGen authors.