Messages while (re)installing portupgrade

[Ronald F. Guilmette]

Because I just switched from ruby1.8 to ruby1.9 I've had to
rebuild and reinstall my ports-mgmt/portupgrade port.  That all
went well, but I got some messages at the end of the re-install
process that I've never noticed before, and they are all rather
befuddling to me:

------------------------------------------------------------------------------
      Fill ALT_PKGDEP section in pkgtools.conf file for portupgrade to be
      aware of alternative dependencies you use.
      E.g.
      ALT_PKGDEP = {
        # Use the -nox11 port when another port depends on category/portexample
        'category/portexample' => 'category/portexample-nox11',
      }

      Note also, portupgrade knows nothing about how to handle ports with
      different suffixes (E.g. -nox11). So you should explicitly define
      variables (E.g. WITHOUT_X11=yes) for the ports in /etc/make.conf or
      pkgtools.conf (MAKE_ARGS section) files.
------------------------------------------------------------------------------

I have no idea what any of the above means.  Should I be at all concerned?

Where exactly is this alleged "pkgtools.conf" file.  I looked in /etc.
It ain't there.  I've never even heard of it until today.

I grok the general idea that there may be a file someplace (called
"pkgtools.conf") wherein one may explicitly override various otherwise
hardwired inter-port dependencies, but what has that got to do with
me?

I _do_ use X, so none of the rest of this stuff seems the least bit
relevant to anything I am doing.  Am I perhaps mistaken?