why are RATS ISOs smaller than usual?

Wed Jan 25 23:47:39 UTC 2012

The usual size of a DVD ISO is about 3.5G. The RATS DVD ISOs at
http://dl.fedoraproject.org/pub/alt/stage/20120117/Fedora/ are only about 2.5G
(the netinsts seem to be the usual size). I downloaded them and looked at the
set of packages in the Packages/ directory to compare with F16. The RATS ISOs no
longer have the libreoffice-langpack-* packages. I'm guessing this is
intentional, but it only seems to account for about half the size difference.
(There were about 60 of these on the F16 DVD, and most of them were about 10M.)
Anyone know what accounts for the rest and if the DVD ISOs are expected to be
about this size from now on?