What is file extension “.qxp”?

I've been sent a couple of files with the extension '.qxp' Does anyone know what they are and what software I can open them with?

Thanks,
Simon

.QXP File Extension

File Type QuarkXpress 6 Project
File Format Image File

Common? Yes
File Description QuarkXpress project file; replaces .qxd extension in QuarkXpress 6.0

Program(s) to open a .qxp file Mac / Windows: QuarkXpress

Perfect - thanks mate.

Simon