I realized today that the filters would not work in Windows installations where Moodle is installed inside some directory which had spaces in its name. Since often Moodle winds up somewhere inside the "Program Files" directory, this is a real possibility. With the cooperation of John Forkosh, author of mimeTeX, I found a portable solution. The scripts pix.php for both filters and the mimetex.exe executable have been updated to deal with this problem. Also the debugging scripts have been updated.