User should read and understand the accompanying documentation stored in /exp/rcf/share/X11R5/java/Jack/doc. There is no man page for this utitlity. Please be aware that this is a BETA version of this software and because of this support for the product will be limited.
What is Jack?
Jack is a parser generator that produces parsers written in Java from
grammar specifications written in a lex/yacc-like manner. Besides its
use in bootstrapping itself, Jack has been used in approximately 20
different projects both within and outside Sun. The Jack release
comes with a ready to use grammar for Java.