XPS documents in Windows 7 have the file extension .xps. Although Windows 8 can view and create both XPS files and OXPS files, it is the .oxps format which is the default XPS document format in the new operating system.
Windows 7 or Windows Server 2008 R2 does not support this new .oxps format. The .oxps files are created in Windows 8 when users print to a Microsoft XPS Document Writer (MXDW) printer.
The Microsoft XPS Document Writer allows you to create .xps files using any program that you run on Windows. MXDW is a print-to-file driver that enables a Windows application to create XML Paper Specification (XPS) document files on versions of Windows starting with Windows XP with Service Pack 2 (SP2). Using the MXDW makes it possible for a Windows application to save its content as an XPS document without changing any of the application’s program code.
OXPS to XPS Converter Tool
If you wish to open .oxps format documents in Windows 7, you will have to install the OXPS to XPS Converter Tool.
Using this tool, you will be able to convert the .oxps file created in Windows 8, to an .xps file and the use the XPS Viewer in Windows 7 to view the converted .xps file, says KB2732059.
You can download the tool here:
You can also use XPSConverter, a command line tool, to convert OXPS files to the XPS file format. The syntax to convert an OXPS file to the XPS format is:
XpsConverter /XPS /InputFile=sample.oxps /OutputFile=sample.xps
Hope it helps!