This package provides development files for the x.org ('xorg') x server. this is not quite the same as the ddk (driver development kit) from the xfree86 4.x and x.org 6.7, 6.8 and 6.9 series of servers; it provides headers and a pkg-config file for drivers using autotools to build against.
unless you are developing or building a driver, you probably want xserver-xorg and/or xserver-xorg-core instead.
more information about x.org can be found at:
this package is built from the x.org xserver module.