PORTSUPDATING -is it too terse for users to be useful?

[Vizion]

Hi

Sorry to say I find this extract in PORTSUPDATING a bit too terse. I wonder if there could be some elaboration on the advice given in PORTSUPDATING for those who do not understand the implications. IMHO it is not very helpful to have an absense of procedural detail in such a critical file.
See illustrative questions below--

20070301:
  AFFECTS: users of ports-mgmt/portupgrade*
  AUTHOR: sem at FreeBSD.org

  Because of a bug in previous version, it's recomended you fill ALT_PKGDEP
QUESTION: OK what is this.. what does it do?
  section in pkgtools.conf file for portupgrade be aware of alternative
  dependencies you use,
 
QUESTION: OK what is an alternative dependency? What procedure do we follow to find out which ones we use?

and run pkgdb -L to restore dependencies that was
  lost.

  Example of ALT_PKGDEP section:
  ALT_PKGDEP = {
    'www/apache13' => 'www/apache13-modssl',
    'print/ghostscript-afpl' => 'print/ghostscript-gnu',
  }
QUESTION: Example is fine.. but what is a suffix? How do we identify the ones we need/use?
  Note also, portupgrade knows nothing how to handle ports with different
  suffixes (E.g. -nox11). So you should define explicitly variables 
  (E.g. WITHOUT_X11=yes) for the ports in /etc/make.conf or pkgtools.conf
  (MAKE_ARGS section) files.