pkg://x11-server-xnest-1.2.0-9.4mdv2007.1.i586.rpm:1544271/HEADER  downloads

Name        : x11-server-xnest             Relocations: (not relocateable)
Version     : 1.2.0                             Vendor: Mandriva
Release     : 9.4mdv2007.1                  Build Date: Tue Jan 22 20:05:20 2008
Install date: (not installed)               Build Host: mercury.mandriva.com
Group       : System/X11                    Source RPM: x11-server-1.2.0-9.4mdv2007.1.src.rpm
Size        : 3899022                          License: MIT
Packager    : Mandriva Security Team <security@mandriva.com>
Summary     : A nested X server
Description :
Xnest is an X Window System server which runs in an X window.
Xnest is a 'nested' window server, actually a client of the
real X server, which manages windows and graphics requests
for Xnest, while Xnest manages the windows and graphics
requests for its own clients.

You will need to install Xnest if you require an X server which
will run as a client of your real X server (perhaps for
testing purposes).