The SXW file format was originally created for StarOffice Writer, the word processing application for Sun Microsystem's StarOffice suite. Programs that can open SXW files include StarOffice Writer and OpenOffice.org Writer. To open an SXW file in Microsoft Word, it's usually possible by renaming it as a DOC file.
This format is used to store background images in uncompressed form in the X Windows System user interface for remote server maintenance. It stores a 'dump' or screenshot of the window or background of the client program. It may include different colors depending on the capabilities of the graphics card that is used to create the XWD file.