Special fonts are those that gtroff searches when it cannot find
the requested glyph in the current font. The Symbol font is usually a
special font.
gtroff provides the following two requests to add more special
fonts. See Using Symbols, for a detailed description of the glyph
searching mechanism in gtroff.
Usually, only non-TTY devices have special fonts.
.special [s1 s2 …] ¶.fspecial f [s1 s2 …] ¶Use the special request to define special fonts. Initially, this
list is empty.
Use the fspecial request to designate special fonts only when
font f is active. Initially, this list is empty.
Previous calls to special or fspecial are overwritten;
without arguments, the particular list of special fonts is set to empty.
Special fonts are searched in the order they appear as arguments.
All fonts that appear in a call to special or fspecial
are loaded.
See Using Symbols, for the exact search order of glyphs.