EFF Bar Code 3 of 9 (8 fonts)Fonts belonging to the group of Special alphabets are designed to be used to set text or at least numbers but the shapes they use for letters or numbers are not these that most of us are used to. So, for instance, Braille font is made out of letters but made of dots, or Bar Code fonts are made of letters and/or digits made of vertical bars.
Some of the fonts such as Optical recognition fonts do use standard letters and digits but are made for a special purpose - to be able to be machine read.