[Yum] yum/rpm group question

[Robert G. Brown]

I'm about half way through writing a perl script to create a list of
groups and packages that would recreate an existing install in either
kickstart or via yum, and I encounter my own ignorance.  To help me
avoid RTFM, I entreat the following Enlightenment.

When running yum -y -d 0 grouplist hidden groupname, one gets a results
such as:

Group: Editors
 Required Groups:
   Base
 Default Metapkgs:
   Emacs
 Optional Metapkgs:
   XEmacs
 Default Packages:
   vim-enhanced
 Optional Packages
   vim-X11

Required Groups I have no problem with -- this seems to say that in
order to install the Editors group I have first (or simultaneously)
install the Base group.  Then things get esoteric.  There are at least
the following subcategories that appear:

 Mandatory Packages:
 Default Packages:
 Optional Packages:
 Default Metapkgs:
 Optional Metapkgs:

So, what exactly do these mean?  I'm assuming that Mandatory Packages
are packages in the group that cannot "not" be installed if the group is
installed (removed by means of a "-pkgname" in a kickstart file).  I'm
assuming that Default Packages are ones that are (in addition to the
Mandatory packages) installed when yum installgroup groupname is run or
@Groupname put in a KS file.  It is my belief, then, that in order to
determine what I need to use in a minimal group/package description I
have to basically construct a list consisting of the union of all
mandatory and default packages in all the installed groups, remove them
from the list of all installed packages, and construct as final output
the list of installed groups plus the remainder/modulus standalone
packages.  Plus any AI massaging one might care to do, e.g. add in
-pkgnames to work down from installed groups as required, although in a
lot of cases nobody will care.

However, what the hell are Optional Packages: and Metapkgs in general?
Do I need to worry about (or include) them?  Is my general description
above correct?

Hear me, oh dieties of rpmness and packagification, as I burn this
scented offering...

   rgb

-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu