BRL-CAD bundles and maintains a number of external libraries and tools critical
to its functionality.  These tools are not installed with the distribution, but
are used in various stages of the compilation process.

lemon           http://www.hwaci.com/sw/lemon/    Parser generator, used by obj and step converters
perplex         BRL-CAD project                   Tool to simplify creating re2c scanners, used by obj
                                                  and step converters
re2c            http://re2c.org/                  Scanner/lexer generator, used by obj and step converters
xmltools        http://xmlsoft.org/               Verify DocBook inputs and generate DocBook outputs

