I tried to use evince with a file called 'mathimatica'. Because this file doesn't have an extension evince cannot open it. KGhostView can, gv can, ghostscript can, even gimp can! Evinces says: "Unhandled MIME type: 'application/octet-stream'". That also meens that I cannot use evince with a web browser because every browser saves the file in a temporary directory with a fake name without extension. I also tried to name 'mathimatica' (a pdf file) 'mathimatica.ps'. Evince opened the file without displaying any error but it thought the document contained only 1 page!