Who starts umass-enum?

In a standard (installed off the CD) QNX Neutrino development system, I have
looked through the build files, scripts and documentation and cannot locate
who starts umass-enum. Is it something enum-devices forks off? Or diskboot?
BTW, there is no documentation for umass-enum as far as I can tell.

What is the proper way to change the configuration to have it start
devb-umass with pnp enabled?

Dave G.