# groff(7) - man - phpMan [GROFF(7)](https://www.chedong.com/phpMan.php/man/GROFF/7/markdown) Miscellaneous Information Manual [GROFF(7)](https://www.chedong.com/phpMan.php/man/GROFF/7/markdown) ## NAME groff - a short reference for the GNU roff language ## DESCRIPTION The name _groff_ stands for _GNU_ _roff_ and is the free implementation of the roff type-setting system. See [**roff**(7)](https://www.chedong.com/phpMan.php/man/roff/7/markdown) for a survey and the background of the groff system. This document provides only short descriptions of roff language elements. _Groff:_ _The_ _GNU_ _Im__‐ _plementation_ _of_ _troff_, by Trent A. Fisher and Werner Lemberg, is the primary _groff_ manual, and is written in Texinfo. You can browse it interactively with “info groff”. Historically, the _roff_ _language_ was called _troff_. _groff_ is compatible with the classical system and provides proper extensions. So in GNU, the terms _roff_, _troff_, and _groff_ _language_ could be used as synonyms. However _troff_ slightly tends to refer more to the classical as‐ pects, whereas _groff_ emphasizes the GNU extensions, and _roff_ is the general term for the lan‐ guage. The general syntax for writing groff documents is relatively easy, but writing extensions to the roff language can be a bit harder. The roff language is line-oriented. There are only two kinds of lines, control lines and text lines. The control lines start with a control character, by default a period “**.**” or a single quote “**'**”; all other lines are text lines. **Control** **lines** represent commands, optionally with arguments. They have the following syntax. The leading control character can be followed by a command name; arguments, if any, are sepa‐ rated by spaces (but not tab characters) from the command name and among themselves, for ex‐ ample, .command_name arg1 arg2 For indentation, any number of space or tab characters can be inserted between the leading control character and the command name, but the control character must be on the first posi‐ tion of the line. **Text** **lines** represent the parts that is printed. They can be modified by escape sequences, which are recognized by a leading backslash ‘**\**’. These are in-line or even in-word format‐ ting elements or functions. Some of these take arguments separated by single quotes “**'**”, others are regulated by a length encoding introduced by an open parenthesis ‘**(**’ or enclosed in brackets ‘**[**’ and ‘**]**’. The roff language provides flexible instruments for writing language extension, such as macros. When interpreting macro definitions, the roff system enters a special operating mode, called the **copy** **mode**. The copy mode behaviour can be quite tricky, but there are some rules that ensure a safe us‐ age. 1. Printable backslashes must be denoted as **\e**. To be more precise, **\e** represents the current escape character. To get a backslash glyph, use **\(rs** or **\[rs]**. 2. Double all backslashes. 3. Begin all text lines with the special non-spacing character **\&**. This does not produce the most efficient code, but it should work as a first measure. For better strategies, see the _groff_ Texinfo manual and **groff**___**[tmac**(5)](https://www.chedong.com/phpMan.php/man/tmac/5/markdown). Reading roff source files is easier, just reduce all double backslashes to a single one in all macro definitions. ## GROFF ELEMENTS The roff language elements add formatting information to a text file. The fundamental ele‐ ments are predefined commands and variables that make roff a full-blown programming language. There are two kinds of roff commands, possibly with arguments. **Requests** are written on a line of their own starting with a dot ‘**.**’ or a “**'**”, whereas **Escape** **sequences** are in-line functions and in-word formatting elements starting with a backslash ‘**\**’. The user can define her own formatting commands using the **de** request. These commands are called **macros**, but they are used exactly like requests. Macro packages are pre-defined sets of macros written in the groff language. A user's possibilities to create escape sequences herself is very limited, only special characters can be mapped. The groff language provides several kinds of variables with different interfaces. There are pre-defined variables, but the user can define her own variables as well. **String** variables store character sequences. They are set with the **ds** request and retrieved by the **\*** escape sequences. Strings can have variables. **Register** variables can store numerical values, numbers with a scale unit, and occasionally string-like objects. They are set with the **nr** request and retrieved by the **\n** escape se‐ quences. **Environments** allow the user to temporarily store global formatting parameters like line length, font size, etc. for later reuse. This is done by the **ev** request. **Fonts** are identified either by a name or by an internal number. The current font is chosen by the **ft** request or by the **\f** escape sequences. Each device has special fonts, but the fol‐ lowing fonts are available for all devices. **R** is the standard font Roman. **B** is its **bold** counterpart. The _italic_ font is called **I** and is available everywhere, but on text devices it is displayed as an underlined Roman font. For the graphical output devices, there exist con‐ stant-width pendants of these fonts, **CR**, **CI**, and **CB**. On text devices, all glyphs have a con‐ stant width anyway. **Glyphs** are visual representation forms of **characters**. In groff, the distinction between those two elements is not always obvious (and a full discussion is beyond the scope of this man page). A first approximation is that glyphs have a specific size and colour and are taken from a specific font; they can't be modified any more – characters are the input, and glyphs are the output. As soon as an output line has been generated, it no longer contains characters but glyphs. In this man page, we use either ‘glyph’ or ‘character’, whatever is more appropriate. Moreover, there are some advanced roff elements. A **diversion** stores (formatted) information into a macro for later usage. See **groff**___**[tmac**(5)](https://www.chedong.com/phpMan.php/man/tmac/5/markdown) for more details. A **trap** is a positional condition like a certain number of lines from page top or in a diversion or in the input. Some action can be prescribed to be run automatically when the condition is met. More detailed information and examples can be found in the _groff_ Texinfo manual. ## CONTROL CHARACTERS There is a small set of characters that have a special controlling task in certain condi‐ tions. **.** A dot is only special at the beginning of a line or after the condition in the re‐ quests **if**, **ie**, **el**, and **while**. There it is the control character that introduces a re‐ quest (or macro). By using the **cc** request, the control character can be set to a dif‐ ferent character, making the dot ‘**.**’ a non-special character. In all other positions, it just means a dot character. In text paragraphs, it is ad‐ vantageous to start each sentence at a line of its own. **'** The single quote has two controlling tasks. At the beginning of a line and in the conditional requests it is the non-breaking control character. That means that it in‐ troduces a request like the dot, but with the additional property that this request doesn't cause a linebreak. By using the **c2** request, the non-break control character can be set to a different character. As a second task, it is the most commonly used argument separator in some functional escape sequences (but any pair of characters not part of the argument do work). In all other positions, it denotes the single quote or apostrophe character. Groff pro‐ vides a printable representation with the **\(cq** escape sequence. **"** The double quote is used to enclose arguments in macros (but not in requests and strings). In the **ds** and **as** requests, a leading double quote in the argument is stripped off, making everything else afterwards the string to be defined (enabling leading whitespace). The escaped double quote **\"** introduces a comment. Otherwise, it is not special. Groff provides a printable representation with the **\(dq** escape se‐ quence. **\** The backslash usually introduces an escape sequence (this can be changed with the **ec** request). A printed version of the escape character is the **\e** escape; a backslash glyph can be obtained by **\(rs**. **(** The open parenthesis is only special in escape sequences when introducing an escape name or argument consisting of exactly two characters. In groff, this behaviour can be replaced by the **[]** construct. **[** The opening bracket is only special in groff escape sequences; there it is used to in‐ troduce a long escape name or long escape argument. Otherwise, it is non-special, e.g. in macro calls. **]** The closing bracket is only special in groff escape sequences; there it terminates a long escape name or long escape argument. Otherwise, it is non-special. _space_ Space characters are only functional characters. They separate the arguments in re‐ quests, macros, and strings, and the words in text lines. They are subject to groff's horizontal spacing calculations. To get a defined space width, escape sequences like ‘**\** ’ (this is the escape character followed by a space), **\|**, **\^**, or **\h** should be used. _newline_ In text paragraphs, newlines mostly behave like space characters. Continuation lines can be specified by an escaped newline, i.e., by specifying a backslash ‘**\**’ as the last character of a line. _tab_ If a tab character occurs during text the interpreter makes a horizontal jump to the next pre-defined tab position. There is a sophisticated interface for handling tab positions. ## NUMERICAL EXPRESSIONS A **numerical** **value** is a signed or unsigned integer or float with or without an appended scal‐ ing indicator. A **scaling** **indicator** is a one-character abbreviation for a unit of measure‐ ment. A number followed by a scaling indicator signifies a size value. By default, numeri‐ cal values do not have a scaling indicator, i.e., they are normal numbers. The _roff_ language defines the following scaling indicators. **c** centimeter **i** inch **P** pica = 1/6 inch **p** point = 1/72 inch **m** em = the font size in points (approx. width of letter ‘m’) **M** 100th of an em **n** en = em/2 **u** Basic unit for actual output device **v** Vertical line space in basic units **s** scaled point = 1/_sizescale_ of a point (defined in font _DESC_ file) **f** Scale by 65536. **Numerical** **expressions** are combinations of the numerical values defined above with the follow‐ ing arithmetical operators already defined in classical troff. **+** Addition **-** Subtraction ***** Multiplication **/** Division **%** Modulo **=** Equals **==** Equals **<** Less than **>** Greater than **<=** Less or equal **>=** Greater or equal **&** Logical and **:** Logical or **!** Logical not **(** Grouping of expressions **)** Close current grouping Moreover, _groff_ added the following operators for numerical expressions: _e1_**>?**_e2_ The maximum of _e1_ and _e2_. _e1_**0. **.ll** Change to previous line length. **.ll** _±_N_ Set line length according to _±_N_ (default length 6.5**i**, default scaling indicator **m**). **.lsm** Unset the leading spaces macro. **.lsm** _macro_ Set the leading spaces macro to _macro_. **.ls** Change to the previous value of additional intra-line skip. **.ls** _N_ Set additional intra-line skip value to _N_, i.e., _N_-1 blank lines are inserted after each text output line. **.lt** _±_N_ Length of title (default scaling indicator **m**). **.mc** Margin glyph off. **.mc** _c_ Print glyph _c_ after each text line at actual distance from right margin. **.mc** _c_ _N_ Set margin glyph to _c_ and distance to _N_ from right margin (default scaling indica‐ tor **m**). **.mk** [_register_] Mark current vertical position in _register_, or in an internal register used by **.rt** if no argument. **.mso** _file_ The same as **.so** except that _file_ is searched in the tmac directories. **.na** No output-line adjusting. **.ne** Need a one-line vertical space. **.ne** _N_ Need _N_ vertical space (default scaling indicator **v**). **.nf** No filling or adjusting of output lines. **.nh** No hyphenation. **.nm** Number mode off. **.nm** _±_N_ [_M_ [_S_ [_I_]]] In line number mode, set number, multiple, spacing, and indentation. **.nn** Do not number next line. **.nn** _N_ Do not number next _N_ lines. **.nop** _anything_ Always process _anything_. **.nr** _register_ _±_N_ [_M_] Define or modify _register_ using _±_N_ with auto-increment _M_. **.nroff** Make the built-in conditions **n** true and **t** false. **.ns** Turn on no-space mode. **.nx** Immediately jump to end of current file. **.nx** _filename_ Immediately continue processing with file _file_. **.open** _stream_ _filename_ Open _filename_ for writing and associate the stream named _stream_ with it. **.opena** _stream_ _filename_ Like **.open** but append to it. **.os** Output vertical distance that was saved by the **sv** request. **.output** _string_ Emit _string_ directly to intermediate output, allowing leading whitespace if _string_ starts with **"** (which is stripped off). **.pc** Reset page number character to ‘**%**’. **.pc** _c_ Page number character. **.pev** Print the current environment and each defined environment state to stderr. **.pi** _program_ Pipe output to _program_ (nroff only). **.pl** Set page length to default 11**i**. The current page length is stored in register **.p**. **.pl** _±_N_ Change page length to _±_N_ (default scaling indicator **v**). **.pm** Print macro names and sizes (number of blocks of 128 bytes). **.pm** _t_ Print only total of sizes of macros (number of 128 bytes blocks). **.pn** _±_N_ Next page number _N_. **.pnr** Print the names and contents of all currently defined number registers on stderr. **.po** Change to previous page offset. The current page offset is available in register **.o**. **.po** _±_N_ Page offset _N_. **.ps** Return to previous point size. **.ps** _±_N_ Point size; same as **\s[**_±_N_**]**. **.psbb** _filename_ Get the bounding box of a PostScript image _filename_. **.pso** _command_ This behaves like the **so** request except that input comes from the standard output of _command_. **.ptr** Print the names and positions of all traps (not including input line traps and di‐ version traps) on stderr. **.pvs** Change to previous post-vertical line spacing. **.pvs** _±_N_ Change post-vertical line spacing according to _±_N_ (default scaling indicator **p**). **.rchar** _c1_ _c2_ ... Remove the definitions of entities _c1_, _c2_, ... **.rd** _prompt_ Read insertion. **.return** Return from a macro. **.return** _anything_ Return twice, namely from the macro at the current level and from the macro one level higher. **.rfschar** _f_ _c1_ _c2_ ... Remove the definitions of entities _c1_, _c2_, ... for font _f_. **.rj** _n_ Right justify the next _n_ input lines. **.rm** _name_ Remove request, macro, diversion, or string _name_. **.rn** _old_ _new_ Rename request, macro, diversion, or string _old_ to _new_. **.rnn** _reg1_ _reg2_ Rename register _reg1_ to _reg2_. **.rr** _register_ Remove _register_. **.rs** Restore spacing; turn no-space mode off. **.rt** Return _(upward_ _only)_ to vertical position marked by **.mk** on the current page. **.rt** _±_N_ Return _(upward_ _only)_ to specified distance from the top of the page (default scal‐ ing indicator **v**). **.schar** _c_ _anything_ Define global fallback character (or glyph) _c_ as string _anything_. **.shc** Reset soft hyphen glyph to **\(hy**. **.shc** _c_ Set the soft hyphen glyph to _c_. **.shift** _n_ In a macro, shift the arguments by _n_ positions. **.sizes** _s1_ _s2_ ... _s_n [**0**] Set available font sizes similar to the **sizes** command in a _DESC_ file. **.so** _filename_ Include source file. **.sp** Skip one line vertically. **.sp** _N_ Space vertical distance _N_ up or down according to sign of _N_ (default scaling indi‐ cator **v**). **.special** Reset global list of special fonts to be empty. **.special** _s1_ _s2_ ... Fonts _s1_, _s2_, etc. are special and are searched for glyphs not in the current font. ### .spreadwarn Toggle the spread warning on and off without changing its value. **.spreadwarn** _limit_ Emit a warning if each space in an output line is widened by _limit_ or more (default scaling indicator **m**). **.ss** _N_ Set space glyph size to _N_/12 of the space width in the current font. **.ss** _N_ _M_ Set space glyph size to _N_/12 and sentence space size set to _M_/12 of the space width in the current font. **.sty** _n_ _style_ Associate _style_ with font position _n_. **.substring** _xx_ _n1_ _n2_ Replace the string named _xx_ with the substring defined by the indices _n1_ and _n2_. **.sv** Save 1 v of vertical space. **.sv** _N_ Save the vertical distance _N_ for later output with **os** request (default scaling in‐ dicator **v**). **.sy** _command-line_ Execute program _command-line_. **.ta** _T_ _N_ Set tabs after every position that is a multiple of _N_ (default scaling indica‐ tor **m**). **.ta** _n1_ _n2_ ... _n_n **T** _r1_ _r2_ ... _r_n Set tabs at positions _n1_, _n2_, ..., _n_n, then set tabs at _n_n+_m_×_r_n+_r1_ through _n_n+_m_×_r_n+_r_n, where _m_ increments from 0, 1, 2, ... to infinity. **.tc** Remove tab repetition glyph. **.tc** _c_ Set tab repetition glyph to _c_. **.ti** _±_N_ Temporary indent next line (default scaling indicator **m**). **.tkf** _font_ _s1_ _n1_ _s2_ _n2_ Enable track kerning for _font_. **.tl** ’’_left_’’_center_’’_right_’’ Three-part title. **.tm** _anything_ Print _anything_ on stderr. **.tm1** _anything_ Print _anything_ on stderr, allowing leading whitespace if _anything_ starts with **"** (which is stripped off). **.tmc** _anything_ Similar to **.tm1** without emitting a final newline. **.tr** _abcd_... Translate _a_ to _b_, _c_ to _d_, etc. on output. **.trf** _filename_ Transparently output the contents of file _filename_. **.trin** _abcd_... This is the same as the **tr** request except that the **asciify** request uses the charac‐ ter code (if any) before the character translation. **.trnt** _abcd_... This is the same as the **tr** request except that the translations do not apply to text that is transparently throughput into a diversion with **\!**. **.troff** Make the built-in conditions **t** true and **n** false. **.uf** _font_ Set underline font to _font_ (to be switched to by **.ul**). **.ul** _N_ Underline (italicize in troff) _N_ input lines. **.unformat** _diversion_ Unformat space characters and tabs in _diversion_, preserving font information. **.vpt** _n_ Enable vertical position traps if _n_ is non-zero, disable them otherwise. **.vs** Change to previous vertical base line spacing. **.vs** _±_N_ Set vertical base line spacing to _±_N_ (default scaling indicator **p**). **.warn** _n_ Set warnings code to _n_. **.warnscale** _si_ Set scaling indicator used in warnings to _si_. **.wh** _N_ Remove (first) trap at position _N_. **.wh** _N_ _trap_ Set location trap; negative means from page bottom. **.while** _cond_ _anything_ While condition _cond_ is true, accept _anything_ as input. **.write** _stream_ _anything_ Write _anything_ to the stream named _stream_. **.writec** _stream_ _anything_ Similar to **.write** without emitting a final newline. **.writem** _stream_ _xx_ Write contents of macro or string _xx_ to the stream named _stream_. Besides these standard groff requests, there might be further macro calls. They can origi‐ nate from a macro package (see [**roff**(7)](https://www.chedong.com/phpMan.php/man/roff/7/markdown) for an overview) or from a preprocessor. Preprocessor macros are easy to recognize. They enclose their code between a pair of charac‐ teristic macros. ┌─────────────┬─────────────────┬────────────────┐ │preprocessor │ start macro │ end macro │ ├─────────────┼─────────────────┼────────────────┤ │ **chem** │ **.cstart** │ **.cend** │ │ **eqn** │ **.EQ** │ **.EN** │ │ **grap** │ **.G1** │ **.G2** │ │ **grn** │ **.GS** │ **.GE** │ │ **ideal** │ **.IS** │ **.IE** │ │ │ │ **.IF** │ │ **pic** │ **.PS** │ **.PE** │ │ **refer** │ **.R1** │ **.R2** │ │ **soelim** │ _none_ │ _none_ │ │ **tbl** │ **.TS** │ **.TE** │ ├─────────────┼─────────────────┼────────────────┤ │ **glilypond** │ **.lilypond** **start** │ **.lilypond** **stop** │ │ **gperl** │ **.Perl** **start** │ **.Perl** **stop** │ │ **gpinyin** │ **.pinyin** **start** │ **.pinyin** **stop** │ └─────────────┴─────────────────┴────────────────┘ Note that the ‘ideal’ preprocessor is not available in groff yet. ## ESCAPE SEQUENCES Escape sequences are in-line language elements usually introduced by a backslash ‘**\**’ and fol‐ lowed by an escape name and sometimes by a required argument. Input processing is continued directly after the escaped character or the argument (without an intervening separation char‐ acter). So there must be a way to determine the end of the escape name and the end of the argument. This is done by enclosing names (escape name and arguments consisting of a variable name) by a pair of brackets **[**_name_**]** and constant arguments (number expressions and characters) by apos‐ trophes (ASCII 0x27) like ’’_constant_’’. There are abbreviations for short names. Two-character escape names can be specified by an opening parenthesis like **\(**xy or **\*(**xy without a closing counterpart. And all one-character names different from the special characters ‘**[**’ and ‘**(**’ can even be specified without a marker, for example **\n**c or **\$**c. Constant arguments of length 1 can omit the marker apostrophes, too, but there is no two- character analogue. While one-character escape sequences are mainly used for in-line functions and system-related tasks, the two-letter names following the **\(** construct are glyphs predefined by the roff sys‐ tem; these are called ‘Special Characters’ in the classical documentation. Escapes sequences of the form **\[**_name_**]** denote glyphs too. ### Single-Character Escapes **\"** Start of a comment. Everything up to the end of the line is ignored. **\#** Everything up to and including the next newline is ignored. This is interpreted in copy mode. This is like **\"** except that the terminating newline is ignored as well. **\***_s_ The string stored in the string variable with one-character name _s_. **\*(**_st_ The string stored in the string variable with two-character name _st_. **\*[**_string_**]** The string stored in the string variable with name _string_ (with arbitrary length). **\*[**_stringvar_ _arg1_ _arg2_ ...**]** The string stored in the string variable with arbitrarily long name _stringvar_, taking _arg1_, _arg2_, ... as arguments. **\$0** The name by which the current macro was invoked. The **als** request can make a macro have more than one name. **\$**_x_ Macro or string argument with one-digit number _x_ in the range 1 to 9. **\$(**_xy_ Macro or string argument with two-digit number _xy_ (larger than zero). **\$[**_nexp_**]** Macro or string argument with number _nexp_, where _nexp_ is a numerical expression evalu‐ ating to an integer ≥1. **\$*** In a macro or string, the concatenation of all the arguments separated by spaces. **\$@** In a macro or string, the concatenation of all the arguments with each surrounded by double quotes, and separated by spaces. **\$^** In a macro, the representation of all parameters as if they were an argument to the **ds** request. **\\** reduces to a single backslash; useful to delay its interpretation as escape character in copy mode. For a printable backslash, use **\e**, or even better **\[rs]**, to be indepen‐ dent from the current escape character. **\**´´ The acute accent ´; same as **\(aa**. Unescaped: apostrophe, right quotation mark, single quote (ASCII 0x27). **\`** The grave accent `; same as **\(ga**. Unescaped: left quote, backquote (ASCII 0x60). **\-** The - (minus) sign in the current font. **\**___ The same as **\(ul**, the underline character. **\.** The same as a dot (‘.’). Necessary in nested macro definitions so that ‘\\..’ expands to ‘..’. **\%** Default optional hyphenation character. **\!** Transparent line indicator. **\?**_anything_**?** In a diversion, this transparently embeds _anything_ in the diversion. _anything_ is read in copy mode. See also the escape sequences **\!** and **\?**. **\**_space_ Unpaddable space size space glyph (no line break). **\0** Digit-width space. **\|** 1/6 em narrow space glyph; zero width in nroff. **\^** 1/12 em half-narrow space glyph; zero width in nroff. **\&** Non-printable, zero-width glyph. **\)** Like **\&** except that it behaves like a glyph declared with the **cflags** request to be transparent for the purposes of end-of-sentence recognition. **\/** Increases the width of the preceding glyph so that the spacing between that glyph and the following glyph is correct if the following glyph is a roman glyph. **\,** Modifies the spacing of the following glyph so that the spacing between that glyph and the preceding glyph is correct if the preceding glyph is a roman glyph. **\~** Unbreakable space that stretches like a normal inter-word space when a line is ad‐ justed. **\:** Inserts a zero-width break point (similar to **\%** but without a soft hyphen character). **\**_newline_ Ignored newline, for continuation lines. **\{** Begin conditional input. **\}** End conditional input. **\(**_sc_ A glyph with two-character name _sc_; see section “Special Characters” below. **\[**_name_**]** A glyph with name _name_ (of arbitrary length). **\[**_comp1_ _comp2_ ...**]** A composite glyph with components _comp1_, _comp2_, ... **\a** Non-interpreted leader character. **\A**’’_anything_’’ If _anything_ is acceptable as a name of a string, macro, diversion, register, environ‐ ment or font it expands to 1, and to 0 otherwise. **\b**’’_abc_...’’ Bracket building function. **\B**’’_anything_’’ If _anything_ is acceptable as a valid numeric expression it expands to 1, and to 0 oth‐ erwise. **\c** Continue output line at next input line. Anything after this escape on the same line is ignored except **\R** (which works as usual). Anything before **\c** on the same line is appended to the current partial output line. The next non-command line after a line interrupted with **\c** counts as a new input line. **\C**’’_glyph_’’ The glyph called _glyph_; same as **\[**_glyph_**]**, but compatible to other roff versions. **\d** Forward (down) 1/2 em (1/2 line in nroff). **\D**’’_charseq_’’ Draw a graphical element defined by the characters in _charseq_; see the _groff_ Texinfo manual for details. **\e** Printable version of the current escape character. **\E** Equivalent to an escape character, but is not interpreted in copy mode. **\f**_F_ Change to font with one-character name or one-digit number _F_. **\fP** Switch back to previous font. **\f(**_fo_ Change to font with two-character name or two-digit number _fo_. **\f[**_font_**]** Change to font with arbitrarily long name or number expression _font_. **\f[]** Switch back to previous font. **\F**_f_ Change to font family with one-character name _f_. **\F(**_fm_ Change to font family with two-character name _fm_. **\F[**_fam_**]** Change to font family with arbitrarily long name _fam_. **\F[]** Switch back to previous font family. **\g**_r_ Return format of register with one-character name _r_ suitable for **af** request. **\g(**_rg_ Return format of register with two-character name _rg_ suitable for **af** request. **\g[**_reg_**]** Return format of register with arbitrarily long name _reg_ suitable for **af** request. **\h**’’_N_’’ Local horizontal motion; move right _N_ (left if negative). **\H**’’_N_’’ Set height of current font to _N_. **\k**_r_ Mark horizontal input place in one-character register _r_. **\k(**_rg_ Mark horizontal input place in two-character register _rg_. **\k[**_reg_**]** Mark horizontal input place in register with arbitrarily long name _reg_. **\l**’’_Nc_’’ Horizontal line drawing function (optionally using character _c_). **\L**’’_Nc_’’ Vertical line drawing function (optionally using character _c_). **\m**_c_ Change to color with one-character name _c_. **\m(**_cl_ Change to color with two-character name _cl_. **\m[**_color_**]** Change to color with arbitrarily long name _color_. **\m[]** Switch back to previous color. **\M**_c_ Change filling color for closed drawn objects to color with one-character name _c_. **\M(**_cl_ Change filling color for closed drawn objects to color with two-character name _cl_. **\M[**_color_**]** Change filling color for closed drawn objects to color with arbitrarily long name _color_. **\M[]** Switch to previous fill color. **\n**_r_ The numerical value stored in the register variable with the one-character name _r_. **\n(**_re_ The numerical value stored in the register variable with the two-character name _re_. **\n[**_reg_**]** The numerical value stored in the register variable with arbitrarily long name _reg_. **\N**’’_n_’’ Typeset the glyph with index _n_ in the current font. No special fonts are searched. Useful for adding (named) entities to a document using the **char** request and friends. **\o**’’_abc_...’’ Overstrike glyphs _a_, _b_, _c_, etc. **\O0** Disable glyph output. Mainly for internal use. **\O1** Enable glyph output. Mainly for internal use. **\p** Break output line at next word boundary; adjust if applicable. **\r** Reverse 1 em vertical motion (reverse line in nroff). **\R**’’_name_ _±_n_’’ The same as **.nr** _name_ _±_n_. **\s**_±_N_ Set/increase/decrease the point size to/by _N_ scaled points; _N_ is a one-digit number in the range 1 to 9. Same as **ps** request. **\s(**_±_N_ **\s**±±**(**_N_ Set/increase/decrease the point size to/by _N_ scaled points; _N_ is a two-digit number ≥1. Same as **ps** request. **\s[**_±_N_**]** **\s**±±**[**_N_**]** **\s**’’_±_N_’’ **\s**±±’’_N_’’ Set/increase/decrease the point size to/by _N_ scaled points. Same as **ps** request. **\S**’’_N_’’ Slant output by _N_ degrees. **\t** Non-interpreted horizontal tab. **\u** Reverse (up) 1/2 em vertical motion (1/2 line in nroff). **\v**’’_N_’’ Local vertical motion; move down _N_ (up if negative). **\V**_e_ The contents of the environment variable with one-character name _e_. **\V(**_ev_ The contents of the environment variable with two-character name _ev_. **\V[**_env_**]** The contents of the environment variable with arbitrarily long name _env_. **\w**’’_string_’’ The width of the glyph sequence _string_. **\x**’’_N_’’ Extra line-space function (negative before, positive after). **\X**’’_string_’’ Output _string_ as device control function. **\Y**_n_ Output string variable or macro with one-character name _n_ uninterpreted as device con‐ trol function. **\Y(**_nm_ Output string variable or macro with two-character name _nm_ uninterpreted as device control function. **\Y[**_name_**]** Output string variable or macro with arbitrarily long name _name_ uninterpreted as de‐ vice control function. **\z**_c_ Print _c_ with zero width (without spacing). **\Z**’’_anything_’’ Print _anything_ and then restore the horizontal and vertical position; _anything_ may not contain tabs or leaders. The escape sequences **\e**, **\.**, **\"**, **\$**, **\***, **\a**, **\n**, **\t**, **\g**, and **\**_newline_ are interpreted in copy mode. Escape sequences starting with **\(** or **\[** do not represent single character escape sequences, but introduce escape names with two or more characters. If a backslash is followed by a character that does not constitute a defined escape sequence, the backslash is silently ignored and the character maps to itself. ### Special Characters [Note: ‘Special Characters’ is a misnomer; those entities are (output) glyphs, not (input) characters.] Common special characters are predefined by escape sequences of the form **\(**_xy_ with characters _x_ and _y_. In _groff_, it is also possible to use the writing **\[**_xy_**]** as well. Some of these special characters exist in the usual font while most of them are only avail‐ able in the special font. Below you can see a small selection of the most important glyphs; a complete list can be found in **groff**___**[char**(7)](https://www.chedong.com/phpMan.php/man/char/7/markdown). **\(Do** Dollar **$** **\(Eu** Euro €€ **\(Po** British pound sterling ££ **\(aq** Apostrophe quote **'** **\(bu** Bullet sign •• **\(co** Copyright ©© **\(cq** Single closing quote (right) ’’ **\(ct** Cent ¢¢ **\(dd** Double dagger ‡‡ **\(de** Degree °° **\(dg** Dagger †† **\(dq** Double quote (ASCII 34) **"** **\(em** Em-dash —— **\(en** En-dash –– **\(hy** Hyphen ‐‐ **\(lq** Double quote left ““ **\(oq** Single opening quote (left) ‘‘ **\(rg** Registered sign ®® **\(rq** Double quote right ”” **\(rs** Printable backslash character **\** **\(sc** Section sign §§ **\(tm** Trademark symbol ™™ **\(ul** Underline character ___ **\(==** Identical ≡≡ **\(>=** Larger or equal ≥≥ **\(<=** Less or equal ≤≤ **\(!=** Not equal ≠≠ **\(->** Right arrow →→ **\(<-** Left arrow ←← **\(+-** Plus-minus sign ±± ### Unicode Characters The extended escape **u** allows the inclusion of all available Unicode characters into a _roff_ file. **\[u**_xxxx_**]** **u** is the escape name. _xxxx_ is a hexadecimal number of four hex digits, such as **0041** for the letter **A**, thus **\[u0041]**. **\[u**_yyyyy_**]** **u** is the escape name. _yyyyy_ is a hexadecimal number of five hex digits, such as **2FA1A** for a Chinese-looking character from the Unicode block _CJK_ _Compatibility_ _Ideographs_ _Supplement_, thus **\[u2FA1A]**. The hexadecimal value indicates the corresponding Unicode code point for a character. **\[u**_hex1_hex2_**]** **\[u**_hex1_hex2_hex3_**]** _hex1_, _hex2_, and _hex3_ are all Unicode hexadecimal codes (4 or 5 hex digits) that are used for overstriking, e.g. **\[u0041**___**0301]** is _A_ _acute_, which can also be specified as ÁÁ; see **groff**___**[char**(7)](https://www.chedong.com/phpMan.php/man/char/7/markdown). The availability of the Unicode characters depends on the font used. For text mode, the de‐ vice **-Tutf8** is quite complete; for _troff_ modes it might happen that some or many characters will not be displayed. Please check your fonts. ### Strings Strings are defined by the **ds** request and can be retrieved by the **\*** escape sequence. Strings share their name space with macros. So strings and macros without arguments are roughly equivalent; it is possible to call a string like a macro and vice versa, but this of‐ ten leads to unpredictable results. The following string is the only one predefined in groff. \*[**.T**] The name of the current output device as specified by the **-T** command-line option. ## REGISTERS Registers are variables that store a value. In groff, most registers store numerical values (see section “Numerical Expressions” above), but some can also hold a string value. Each register is given a name. Arbitrary registers can be defined and set with the **nr** re‐ quest. The value stored in a register can be retrieved by the escape sequences introduced by **\n**. Most useful are predefined registers. In the following the notation _name_ is used to refer to register **name** to make clear that we speak about registers. Please keep in mind that the **\n[]** decoration is not part of the register name. ### Read-only Registers The following registers have predefined values that should not be modified by the user (usu‐ ally, registers starting with a dot are read-only). Mostly, they provide information on the current settings or store results from request calls. \n[**$$**] The process ID of **troff**. \n[**.$**] Number of arguments in the current macro or string. \n[**.a**] Post-line extra line-space most recently utilized using **\x**. \n[**.A**] Set to 1 in **troff** if option **-A** is used; always 1 in **nroff**. \n[**.b**] The emboldening offset while **.bd** is active. \n[**.br**] Within a macro, set to 1 if macro called with the ‘normal’ control character, and to 0 otherwise. \n[**.c**] Current input line number. \n[**.C**] 1 if compatibility mode is in effect, 0 otherwise. \n[**.cdp**] The depth of the last glyph added to the current environment. It is positive if the glyph extends below the baseline. \n[**.ce**] The number of lines remaining to be centered, as set by the **ce** request. \n[**.cht**] The height of the last glyph added to the current environment. It is positive if the glyph extends above the baseline. \n[**.color**] 1 if colors are enabled, 0 otherwise. \n[**.csk**] The skew of the last glyph added to the current environment. The skew of a glyph is how far to the right of the center of a glyph the center of an accent over that glyph should be placed. \n[**.d**] Current vertical place in current diversion; equal to register **nl**. \n[**.ev**] The name or number of the current environment (string-valued). \n[**.f**] Current font number. \n[**.F**] The name of the current input file (string-valued). \n[**.fam**] The current font family (string-valued). \n[**.fn**] The current (internal) real font name (string-valued). \n[**.fp**] The number of the next free font position. \n[**.g**] Always 1 in GNU troff. Macros should use it to test if running under groff. \n[**.h**] Text base-line high-water mark on current page or diversion. \n[**.H**] Number of basic units per horizontal unit of output device resolution. \n[**.height**] The current font height as set with **\H**. \n[**.hla**] The current hyphenation language as set by the **hla** request. \n[**.hlc**] The number of immediately preceding consecutive hyphenated lines. \n[**.hlm**] The maximum allowed number of consecutive hyphenated lines, as set by the **hlm** re‐ quest. \n[**.hy**] The current hyphenation flags (as set by the **hy** request). \n[**.hym**] The current hyphenation margin (as set by the **hym** request). \n[**.hys**] The current hyphenation space (as set by the **hys** request). \n[**.i**] Current indentation. \n[**.in**] The indentation that applies to the current output line. \n[**.int**] Positive if last output line contains **\c**. \n[**.j**] The current adjustment mode. It can be stored and used to set adjustment. (n = 1, b = 1, l = 0, r = 5, c = 3). \n[**.k**] The current horizontal output position (relative to the current indentation). \n[**.kern**] 1 if pairwise kerning is enabled, 0 otherwise. \n[**.l**] Current line length. \n[**.L**] The current line spacing setting as set by **.ls**. \n[**.lg**] The current ligature mode (as set by the **lg** request). \n[**.linetabs**] The current line-tabs mode (as set by the **linetabs** request). \n[**.ll**] The line length that applies to the current output line. \n[**.lt**] The title length (as set by the **lt** request). \n[**.m**] The current drawing color (string-valued). \n[**.M**] The current background color (string-valued). \n[**.n**] Length of text portion on previous output line. \n[**.ne**] The amount of space that was needed in the last **ne** request that caused a trap to be sprung. Useful in conjunction with register **.trunc**. \n[**.ns**] 1 if in no-space mode, 0 otherwise. \n[**.o**] Current page offset. \n[**.O**] The suppression nesting level (see **\O**). \n[**.p**] Current page length. \n[**.P**] 1 if the current page is being printed, 0 otherwise (as determined by the **-o** com‐ mand-line option). \n[**.pe**] 1 during page ejection, 0 otherwise. \n[**.pn**] The number of the next page: either the value set by a **pn** request, or the number of the current page plus 1. \n[**.ps**] The current point size in scaled points. \n[**.psr**] The last-requested point size in scaled points. \n[**.pvs**] The current post-vertical line spacing. \n[**.R**] The number of unused number registers. Always 10000 in GNU troff. \n[**.rj**] The number of lines to be right-justified as set by the **rj** request. \n[**.s**] Current point size as a decimal fraction. \n[**.slant**] The slant of the current font as set with **\S**. \n[**.sr**] The last requested point size in points as a decimal fraction (string-valued). \n[**.ss**] The value of the parameters set by the first argument of the **ss** request. \n[**.sss**] The value of the parameters set by the second argument of the **ss** request. \n[**.sty**] The current font style (string-valued). \n[**.t**] Vertical distance to the next trap. \n[**.T**] Set to 1 if option **-T** is used. \n[**.tabs**] A string representation of the current tab settings suitable for use as an argument to the **ta** request. \n[**.trunc**] The amount of vertical space truncated by the most recently sprung vertical posi‐ tion trap, or, if the trap was sprung by an **ne** request, minus the amount of verti‐ cal motion produced by **.ne**. Useful in conjunction with the register **.ne**. \n[**.u**] Equal to 1 in fill mode and 0 in no-fill mode. \n[**.U**] Equal to 1 in safer mode and 0 in unsafe mode. \n[**.v**] Current vertical line spacing. \n[**.V**] Number of basic units per vertical unit of output device resolution. \n[**.vpt**] 1 if vertical position traps are enabled, 0 otherwise. \n[**.w**] Width of previous glyph. \n[**.warn**] The sum of the number codes of the currently enabled warnings. \n[**.x**] The major version number. \n[**.y**] The minor version number. \n[**.Y**] The revision number of groff. \n[**.z**] Name of current diversion. \n[**.zoom**] Zoom factor for current font (in multiples of 1/1000th; zero if no magnification). ### Writable Registers The following registers can be read and written by the user. They have predefined default values, but these can be modified for customizing a document. \n[**%**] Current page number. \n[**c.**] Current input line number. \n[**ct**] Character type (set by width function **\w**). \n[**dl**] Maximal width of last completed diversion. \n[**dn**] Height of last completed diversion. \n[**dw**] Current day of week (1–7). \n[**dy**] Current day of month (1–31). \n[**hours**] The number of hours past midnight. Initialized at start-up. \n[**hp**] Current horizontal position at input line. \n[**llx**] Lower left x-coordinate (in PostScript units) of a given PostScript image (set by **.psbb**). \n[**lly**] Lower left y-coordinate (in PostScript units) of a given PostScript image (set by **.psbb**). \n[**ln**] Output line number. \n[**lsn**] The number of leading spaces of an input line. \n[**lss**] The horizontal space corresponding to the leading spaces of an input line. \n[**minutes**] The number of minutes after the hour. Initialized at start-up. \n[**mo**] Current month (1–12). \n[**nl**] Vertical position of last printed text base-line. \n[**opmaxx**] \n[**opmaxy**] \n[**opminx**] \n[**opminy**] These four registers mark the top left and bottom right hand corners of a box which encompasses all written glyphs. They are reset to -1 by **\O**_0_ or **\O**_1_. \n[**rsb**] Like register **sb**, but takes account of the heights and depths of glyphs. \n[**rst**] Like register **st**, but takes account of the heights and depths of glyphs. \n[**sb**] Depth of string below base line (generated by width function **\w**). \n[**seconds**] The number of seconds after the minute. Initialized at start-up. \n[**skw**] Right skip width from the center of the last glyph in the **\w** argument. \n[**slimit**] If greater than 0, the maximum number of objects on the input stack. If ≤0 there is no limit, i.e., recursion can continue until virtual memory is exhausted. \n[**ssc**] The amount of horizontal space (possibly negative) that should be added to the last glyph before a subscript (generated by width function **\w**). \n[**st**] Height of string above base line (generated by width function **\w**). \n[**systat**] The return value of the _system()_ function executed by the last **sy** request. \n[**urx**] Upper right x-coordinate (in PostScript units) of a given PostScript image (set by **.psbb**). \n[**ury**] Upper right y-coordinate (in PostScript units) of a given PostScript image (set by **.psbb**). \n[**year**] The current year (year 2000 compliant). \n[**yr**] Current year minus 1900. For Y2K compliance use register **year** instead. ## HYPHENATION The **.hy** request, given an integer argument, controls when hyphenation applies. The default value is **1**, which enables hyphenation almost everywhere (see below). Macro packages often override this default. **1** disables hyphenation only after the first and before the last character of a word. **2** disables hyphenation only of the last word on a page or column. **4** disables hyphenation only before the last two characters of a word. **8** disables hyphenation only after the first two characters of a word. **16** enables hyphenation before the last character of a word. **32** enables hyphenation after the first character of a word. The values are additive. Some values cannot be used together because they contradict; for instance, 4 and 16; 8 and 32. ## UNDERLINING In the _RUNOFF_ language, the underlining was quite easy. But in _roff_ this is much more diffi‐ cult. ### Underlining with .ul There exists a _groff_ request **.ul** (see above) that can underline the next or further source lines in **nroff**, but in **troff** it produces only a font change into _italic_. So this request is not really useful. ### Underlining with .UL from ms In the ‘ms’ macro package in tmac/s.tmac **groff**___**[ms**(7)](https://www.chedong.com/phpMan.php/man/ms/7/markdown), there is the macro **.UL**. But this works only in **troff**, not in **nroff**. ### Underlining macro definitions So one can use the _italic_ **nroff** idea from **.ul** and the **troff** definition in _ms_ for writing a useful new macro, something like .de UNDERLINE . ie n \\$1\f[I]\\$2\f[P]\\$3 . el \\$1\Z'\\$2'\v'.25m'\D'l \w'\\$2'u 0'\v'-.25m'\\$3 .. If [**doclifter**(1)](https://www.chedong.com/phpMan.php/man/doclifter/1/markdown) makes trouble, change the macro name **UNDERLINE** into some 2-letter word, like **Ul**. Moreover change the font writing from **\f[P]** to **\fP**. ### Underlining without macro definitions If one does not want to use macro definitions, e.g., when **doclifter** gets lost, use the fol‐ lowing: .ds u1 before .ds u2 in .ds u3 after .ie n \*[u1]\f[I]\*[u2]\f[P]\*[u3] .el \*[u1]\Z'\*[u2]'\v'.25m'\D'l \w'\*[u2]'u 0'\v'-.25m'\*[u3] Due to **doclifter**, it might be necessary to change the variable writing **\[xy]** and **\*[xy]** into the strange ancient writing **\*(xy** and **\(xy**, and so on. Then these lines could look like .ds u1 before .ds u2 in .ds u3 after .ie n \*[u1]\fI\*(u2\fP\*(u3 .el \*(u1\Z'\*(u2'\v'.25m'\D'l \w'\*(u2'u 0'\v'-.25m'\*(u3 The result looks like before _in_ after ### Underlining with Overstriking \z and \(ul There is another possibility for underlining by using overstriking with **\z**_c_ (print _c_ with zero width without spacing) and **\(ul** (underline character). This produces the underlining of 1 character, both in **nroff** and in **troff**. For example the underlining of a character say **t** looks like **\z\[ul]t** or **\z\(ult** Longer words look then a bit strange, but a useful mode is to write each character into a whole own line. To underlines the 3 character part "tar" of the word "start": before s\ \z\[ul]t\ \z\[ul]a\ \z\[ul]r\ t after or before s\ \z\(ult\ \z\(ula\ \z\(ulr\ t after The result looks like before s_tar_t after ## COMPATIBILITY The differences between the groff language and classical troff as defined by [CSTR #54] are documented in **groff**___**[diff**(7)](https://www.chedong.com/phpMan.php/man/diff/7/markdown). The groff system provides a compatibility mode, see [**groff**(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown) on how to invoke this. ## AUTHORS This document was written by Bernd Warken ⟨⟩. ## SEE ALSO _Groff:_ _The_ _GNU_ _Implementation_ _of_ _troff_, by Trent A. Fisher and Werner Lemberg, is the primary _groff_ manual. You can browse it interactively with “info groff”. Besides the gory details, it contains many examples. [**groff**(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown) the usage of the groff program and pointers to the documentation and availability of the groff system. **groff**___**[diff**(7)](https://www.chedong.com/phpMan.php/man/diff/7/markdown) describes the differences between the groff language and classical troff. This is the authoritative document for the predefined language elements that are spe‐ cific to groff. **groff**___**[char**(7)](https://www.chedong.com/phpMan.php/man/char/7/markdown) the predefined groff special characters (glyphs). **groff**___**[font**(5)](https://www.chedong.com/phpMan.php/man/font/5/markdown) the specification of fonts and the DESC file. **groff**___**[tmac**(5)](https://www.chedong.com/phpMan.php/man/tmac/5/markdown) contains an overview of available groff macro packages, instructions on how to inter‐ face them with a document, guidance on writing macro packages and using diversions, and historical information on macro package naming conventions. [**roff**(7)](https://www.chedong.com/phpMan.php/man/roff/7/markdown) the history of roff, the common parts shared by all roff systems, and pointers to fur‐ ther documentation. [CSTR #54] Nroff/Troff User's Manual by Ossanna & Kernighan ⟨ 54.ps.gz⟩ — the bible for classical troff. _Wikipedia_ article about _groff_ ⟨⟩. _Tutorial_ _about_ _groff_ Manas Laha - An Introduction to the GNU Groff Text Processing System ⟨dl.dropbox.com/ u/4299293/grofftut.pdf⟩ _troff.org_ This is a collection of internet sites with classical _roff_ documentations and other information. groff 1.22.4 23 March 2022 [GROFF(7)](https://www.chedong.com/phpMan.php/man/GROFF/7/markdown)