A character can be generated by typing a "character reference" with its decimal value, e.g., with the default character set `&' will produce & and `<' will produce <.
Character entity sets can be used to obtain special symbols within an SGML document. gf supports 6 entity sets(2):
See Figure 1 in section Character Entity Sets to Figure 6 in section Character Entity Sets for tables showing the characters available. This is not the complete set of ISO character entity sets: others include greek letters and AMS math symbols. Note that the conversion to LaTeX does not support all of the symbols in the supported sets. (figure 1 omitted: ISO Added Latin 1 Character Entity Set) (figure 2 omitted: ISO Added Latin 2 Character Entity Set) (figure 3 omitted: ISO Diacritical Marks Character Entity Set. The marks can be applied to any character, in this case "a". Note: they are applied to the immediately preceding character.) (figure 4 omitted: ISO Publishing Character Entity Set) (figure 5 omitted: ISO Numeric and Special Graphic Character Entity Set. "nbsp" is a space where a line break is forbidden. "shy" is a soft hyphen, which allows a linebreak with the insertion of a hyphen.) (figure 6 omitted: ISO General Technical Character Entity Set. Math operators are classed as relations, binary operators, etc., and include implicit spacing.)
A symbol can be used by entering the appropriate entity reference, e.g., `—' will generate "---" when the document is formatted.
It is possible to modify the generated characters or define new characters if this is permitted for a given DTD: see section Control of Character Entity Translation.