R help - Jan 2008 - NLMINB convergence codes

According to the R documentation for NLMINB, the returned value of convergence
is 0 for successful convergence.  When I got another code (1), I looked up the
PDF that linked from the documentation
(http://netlib.bell-labs.com/cm/cs/cstr/153.pdf), which said that a return code
under 3 was impossible.

Is there other documentation that gives the correct meanings of the NLMINB
convergence codes in the R implementation?

Thanks!

Rebecca