differences between sles8 and suse9 autoyast

hi there, am i right that the version delivered with sles8 is not able to handle rules.xml files as described in the documentation of suse9?! what would happen if i install the version for suse9 on sles8 platform?! or how could i get with sles8 these rulebased build mechanism for autoyast.xml files?! and one more question, the final autoyast.xml is parsed and interpreted at installation runtime of the system?! does that mean, if i install sles8 i only can use the sles8 mimic in the autoyast process and if i install suse9 i can use the rulebased mechanisms? that would mean the installation of the suse9 autoyast packages on sles8 wouldn't help to get a rulebased installation process there ... thanks for answers. helge.