As said, it's a simulation file. If you review the UDP core, everything is clear at once. There's a pair of coregen and simulation files for this and a few more components. The spartan version of the simulation file however seems to be broken, there's also a virtex version, that contains a reasonable ROM simulation.
If at least the full file had been shown with the initial post, including the header, most speculations could be avoided. My suggestion is to get an overview of the design structure first before asking questions about individual files or even snippets.