A X True Type Font Server.

NOTE: Name of executable is "xfs.xtt", rather than "xfs".

For more info, See 
  http://cclub.tutcc.tut.ac.jp/%7Ego/unix/xtt.html
or
  http://www.ryukyu.ad.jp/%7Eshin/linux/x-tt/
or
  http://hawk.ise.chuo-u.ac.jp/student/person/tshiozak/study/
         freebsd-at-random/x-tt/index-en.html (in English)

enjoy!