5.19.6 Special Fonts

Special fonts are those that the formatter searches, in mounting position order, when it cannot find a requested glyph in the selected font. Typically, they are declared as such in their description files,¹²² and contain unstyled glyphs. The “Symbol” and “Zapf Dingbats” fonts of the PostScript and PDF standards are examples. Ordinarily, only typesetters have special fonts.

GNU troff’s special and fspecial requests permit a document to supplement the set of fonts the device configures for glyph search without having to use the fp request to manipulate the list of mounting positions, which can be tedious—by default, GNU troff mounts 40 fonts at startup when using the ps device.

Request: .special [s …]

Request: .fspecial f [s …]

special declares each font s as special, irrespective of its description file, populating a list that GNU troff searches, in order, to find the glyph demanded. GNU troff mounts each font s. Invoking special without arguments empties the list. A font is not automatically unmounted if a subsequent special request removes it from the list. Initially, the list is empty.

fspecial is similar; it designates each font s as special only when font f is selected. Initially, a font f’s list of associated special fonts is empty for all f.

Invoking special (or fspecial, for a given font f) again overwrites the previous list; if you invoke them without arguments, GNU troff empties the corresponding list.