If you google PRC you will get pages of things highly unlikely to be
what you want, e.g. People's Republic of China. What does PRC stand
for? Does it have a context, e.g. Palm OS?
If you google withe the link that Daniel Pitts suggested:
<
http://www.google.com/search?q=jar+to+prc>
the evidence points to yes, there is a Palm OS context, and to
solutions to the OP's question. It's a safe bet I should think that
we're talking Palm OS, given the context of conversion from JARs, and
that the pointers to the solutions given via Daniel's link are more
likely to be helpful than affecting not to understand the question.
To the OP: if we have guessed wrong and you aren't talking about Palm
OS resource files, let us know.