msx and msy fonts?The msx and msy fonts were designed by the American Mathematical
Society in the very early days of TeX, for use in typesetting
papers for mathematical journals. They were designed using the 'old'
Metafont, which wasn't portable and is no longer available; for a long
time they were only available in 300dpi versions which only
imperfectly matched modern printers. The AMS has now redesigned the
fonts, using the current version of Metafont, and the new versions are
called the msa and msb families.
Nevertheless, msx and msy continue to turn up to plague us. There
are, of course, still sites that haven't got around to upgrading; but,
even if everyone upgraded, there would still be the problem of old
documents that specify them.
If you have a .tex source that requests msx and msy, the best
technique is to edit it so that it requests msa and msb (you only
need to change the single letter in the font names).
If you have a DVI file that requests the fonts, there is a package of virtual fonts to map the old to the new series.