"Patch Update CD", how to make?

In Yast2, there is a menu option to apply a "Patch Update CD". Simply downloading the current updates from SuSE's website and placing them on a CD does not, however, appear to be sufficient to get it recognized as a Patch Update CD. Searching around in the sdb and online documents, I did not immediately see any notes on how to prepare a CD that would be recognized as a patch update CD. Can someone point me to documentation on how to do this, or perhaps explain it in a response to the list? In case it makes a difference, I'm runing 7.3/i386. Thanks, --Bob Drzyzgula