There isn't much to say. It's just a clean rebuild againt itself.
CentOS 4 offers both yum and up2date to do updates of the operating system. You can use either or both of these to manage your updates. Prior to using yum, you must import the RPM-GPG-KEY for CentOS-4 like this rpm --import /usr/share/doc/centos-release-4/RPM-GPG-KEY anaconda-10.1.1.19-1.centos4.s390.rpm anaconda-help-10.1.0-1.centos4.noarch.rpm anaconda-product-4.0-2.centos4.noarch.rpm anaconda-runtime-10.1.1.19-1.centos4.s390.rpm createrepo-0.4.2-1.noarch.rpm centos-release-4-1.2.s390.rpm centos-yumconf-4-4.2.noarch.rpm dhclient-3.0.1-12_EL.centos4.s390.rpm dhcp-3.0.1-12_EL.centos4.s390.rpm dhcp-devel-3.0.1-12_EL.centos4.s390.rpm firefox-1.0.4-1.4.1.centos4.s390.rpm firstboot-1.3.39-2.centos4.noarch.rpm glade2-2.6.0-1.centos4.s390.rpm gnome-desktop-2.8.0-3.centos4.s390.rpm gnome-desktop-devel-2.8.0-3.centos4.s390.rpm gnome-session-2.8.0-5.centos4.s390.rpm httpd-2.0.52-12.ent.centos4.s390.rpm httpd-devel-2.0.52-12.ent.centos4.s390.rpm httpd-manual-2.0.52-12.ent.centos4.s390.rpm httpd-suexec-2.0.52-12.ent.centos4.s390.rpm indexhtml-4-1.centos4.noarch.rpm initscripts-7.93.13.EL-2.centos4.s390.rpm mod_perl-1.99_16-4.centos4.s390.rpm mod_perl-devel-1.99_16-4.centos4.s390.rpm mod_ssl-2.0.52-12.ent.centos4.s390.rpm mozilla-1.7.8-1.4.1.centos4.s390.rpm mozilla-chat-1.7.8-1.4.1.centos4.s390.rpm mozilla-devel-1.7.8-1.4.1.centos4.s390.rpm mozilla-dom-inspector-1.7.8-1.4.1.centos4.s390.rpm mozilla-js-debugger-1.7.8-1.4.1.centos4.s390.rpm mozilla-mail-1.7.8-1.4.1.centos4.s390.rpm mozilla-nspr-1.7.8-1.4.1.centos4.s390.rpm mozilla-nspr-devel-1.7.8-1.4.1.centos4.s390.rpm mozilla-nss-1.7.8-1.4.1.centos4.s390.rpm mozilla-nss-devel-1.7.8-1.4.1.centos4.s390.rpm redhat-artwork-0.120-1.1E.centos4.1.s390.rpm redhat-logos-1.1.25-1.centos4.3.noarch.rpm rhn-applet-2.1.17-5.centos4.1.s390.rpm squirrelmail-1.4.3a-9.EL4.centos4.noarch.rpm system-config-printer-0.6.116-1.centos4.1.s390.rpm system-config-printer-gui-0.6.116-1.centos4.1.s390.rpm thunderbird-1.0.2-1.4.1.centos4.s390.rpm up2date-4.4.5.6-2.centos4.2.s390.rpm up2date-gnome-4.4.5.6-2.centos4.2.s390.rpm yum-2.2.1-1.centos4.noarch.rpm
libxml2 was taken from earlier builds as it's not compiling anymore with the latest gcc (gcc version 3.4.3 20050227 (Red Hat 3.4.3-22.1)).
It includes all the updates/security fixes up to the zlib-1.2.1.2-1.1
Your CentOS/s390(x) maintainer,
Pasi Pirhonen Note
For more Information, see the CentOS-4 Documentation at CentOS.org, or the /NOTES directory on CD-1 of this distribution. The documentation is provided {and copyrighted} by Red Hat®,Inc. The CentOS Project redistributes these original works (in their unmodified form) as a reference for CentOS-4. CentOS-4 is built from publicly available, open source SRPMs.