groff: Special Fonts
5.17.6 Special Fonts
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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. ⇒Using Symbols, for a detailed description of the glyph
searching mechanism in 'gtroff'.
Usually, only non-TTY devices have special fonts.
-- Request: .special [s1 s2 ...]
-- Request: .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.
⇒Using Symbols, for the exact search order of glyphs.