There is only one file type that uses the .OXPS extension:
An OXPS file is a document saved in the Open XML Paper Specification (OpenXPS) format. It stores information that describes the structure and content of the document and preserves it as a fixed layout similar to .PDF files. OXPS files are often used for saving essays, letters, postcards, newsletters, and business documents.
The OpenXPS format is based on the XML Paper Specification (XPS) format, which was developed by Microsoft as a replacement for the Enhanced Metafile (.EMF) format. However, OpenXPS is an open format that was standardized in June 2009 by Ecma International, which is a standards organization for communication and information systems.
While the OpenXPS format is based on the XPS format, the two formats are not interchangeable. You cannot simply change the .oxps extension of an OXPS file to .xps in order to make it an .XPS file.
Updated: September 28, 2019