what are repocache directories

I run a rsync overnight (during my ISPs free download time) to keep a local
copy of the KDE repositories.
Last night the rsync downloaded over 4500 files including a bundle of
repocache directories containing some oddball file names e.g.

Backports/openSUSE_11.1/repocache/GraphicsMagick-1.3.7-2.1.i586.rpm-6acf826984d7b1a6e547809150c0d04c37af82e2-1203233-1259927340
KDE3/openSUSE_11.1/repocache/kdbg-2.2.0-10.1.i586.rpm-781df08c031f7ac2a30bc438a9eeb039155ffea7-287955-1256578121
KDE4:/UNSTABLE:/Desktop/openSUSE_11.1/repocache/kvpnc-0.9.3-14.40.src.rpm-24c9cd3e1dee45f78f1dd2d1ad6a16ccaddfbe03-576876-1260395789

and the like.

What are these repocache directories and the .rpm-* files in them?

If I don’t need them as repos to keep my local machines up to date I’ll
delete them and filter them out of the rsync but I need to make sure first.

Alan