groff_rfc1345(7)

Name
groff_rfc1345 - special character names from RFC 1345 and Vim digraphs

Description
The file rfc1345.tmac defines special character escape sequences for groff(7) based on the glyph mnemonics specified in RFC 1345 and the digraph table of the text editor Vim. Each escape sequence translates to a Unicode code point, and will render correctly if the underlying font is a Unicode font that covers the code point.

For example, “\[Rx]” is the “recipe” or “prescription take” symbol, and maps to the code point U+211E. groff lets you write it as “\[u211E]”, but “\[Rx]” is more mnemonic.

For a list of the glyph names provided, please see the file rfc1345.tmac, which contains definitions of the form
        .char \[Rx] \[u211E]    \" PRESCRIPTION TAKE
where .char's first argument defines a groff special character escape sequence with a mnemonic glyph name, its second argument is a special character escape sequence based on the code point, and the comment describes the glyph defined.

The RFC 1345 glyph names cover a wide range of Unicode code points, including supplemental Latin, Greek, Cyrillic, Hebrew, Arabic, Hiragana, Katakana, and Bopomofo letters, punctuation, math notation, currency symbols, industrial and entertainment icons, and box-drawing symbols.

The Vim digraph table is largely a subset of RFC 1345 (being limited to two-character mnemonics), but, as a newer implementation, adds several mnemonics not specified in the RFC (Latin capital and small letters W and Y with grave accent, bullet, horizontal ellipsis, quadruple prime, “approaches the limit”, and two mappings each for the Euro and rouble signs). These have also been added to rfc1345.tmac.

rfc1345.tmac contains about 1,700 glyph names. It is not an error to load rfc1345.tmac if your font does not have all the glyphs, as long as it contains the glyphs that you actually use in your document.

The RFC 1345 mnemonics are not identical in every case to the mappings for special character glyph names that are built in to groff; for example, “\[<<]” means the “much less than” sign (U+226A) when rfc1345.tmac is not loaded and this special character is not otherwise defined by a document or macro package. rfc1345.tmac redefines “\[<<]” to the “left-pointing double angle quotation mark” (U+00AB). See groff_char(7) for the full list of predefined special character escape sequences.

  Usage
Load the rfc1345.tmac file. This can be done by either adding “.mso rfc1345.tmac” to your document before the first use of any of the glyph names the macro file defines, or by using the troff(1) option “-m rfc1345” from the shell.

Bugs
As the groff Texinfo manual notes, “[o]nly the current font is checked for ligatures and kerns; neither special fonts nor entities defined with the char request (and its siblings) are taken into account.” Many of the characters defined in rfc1345.tmac are accented Latin letters, and will be affected by this deficiency, producing subpar typography (https://savannah.gnu.org/bugs/?59932).

Files

/usr/share/groff/1.24.1/tmac/rfc1345.tmac
    implements the character mappings.

Authors
rfc1345.tmac was contributed by Dorai Sitaram (ds26gte@yahoo.com).

See also
RFC 1345 (https://tools.ietf.org/html/rfc1345), by Keld Simonsen, June 1992.

The Vim digraph table can be listed using the vim(1) command “:help digraph-table”.

groff_char(7)