# man > GROFF_OUT(5) [GROFF_OUT(5)](https://www.chedong.com/phpMan.php/man/GROFFOUT/5/markdown) File Formats Manual [GROFF_OUT(5)](https://www.chedong.com/phpMan.php/man/GROFFOUT/5/markdown) ## NAME groff_out - groff intermediate output format ## DESCRIPTION This manual page describes the _intermediate_ _output_ format of the GNU [**roff**(7)](https://www.chedong.com/phpMan.php/man/roff/7/markdown) text processing system [**groff**(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown). This output is produced by a run of the GNU [**troff**(1)](https://www.chedong.com/phpMan.php/man/troff/1/markdown) program. It contains already all device-specific information, but it is not yet fed into a device postprocessor program. As the GNU _roff_ processor [**groff**(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown) is a wrapper program around **troff** that automatically calls a postprocessor, this output does not show up normally. This is why it is called _intermedi__‐ _ate_ within the _groff_ _system_. The **groff** program provides the option **-Z** to inhibit postpro‐ cessing, such that the produced _intermediate_ _output_ is sent to standard output just like calling **troff** manually. In this document, the term _troff_ _output_ describes what is output by the GNU **troff** program, while _intermediate_ _output_ refers to the language that is accepted by the parser that prepares this output for the postprocessors. This parser is smarter on whitespace and implements ob‐ solete elements for compatibility, otherwise both formats are the same. Both formats can be viewed directly with [**gxditview**(1)](https://www.chedong.com/phpMan.php/man/gxditview/1/markdown). The main purpose of the _intermediate_ _output_ concept is to facilitate the development of post‐ processors by providing a common programming interface for all devices. It has a language of its own that is completely different from the [**groff**(7)](https://www.chedong.com/phpMan.php/man/groff/7/markdown) language. While the _groff_ language is a high-level programming language for text processing, the _intermediate_ _output_ language is a kind of low-level assembler language by specifying all positions on the page for writing and drawing. The pre-_groff_ _roff_ versions are denoted as _classical_ _troff_. The _intermediate_ _output_ produced by **groff** is fairly readable, while _classical_ _troff_ output was hard to understand because of strange habits that are still supported, but not used any longer by _GNU_ _troff_. ## LANGUAGE CONCEPTS During the run of **troff**, the _roff_ input is cracked down to the information on what has to be printed at what position on the intended device. So the language of the _intermediate_ _output_ format can be quite small. Its only elements are commands with or without arguments. In this document, the term “command” always refers to the _intermediate_ _output_ language, never to the _roff_ language used for document formatting. There are commands for positioning and text writing, for drawing, and for device controlling. ### Separation _Classical_ _troff_ _output_ had strange requirements on whitespace. The **groff** output parser, how‐ ever, is smart about whitespace by making it maximally optional. The whitespace characters, i.e., the _tab_, _space_, and _newline_ characters, always have a syntactical meaning. They are never printable because spacing within the output is always done by positioning commands. Any sequence of _space_ or _tab_ characters is treated as a single _syntactical_ _space_. It sepa‐ rates commands and arguments, but is only required when there would occur a clashing between the command code and the arguments without the space. Most often, this happens when variable length command names, arguments, argument lists, or command clusters meet. Commands and ar‐ guments with a known, fixed length need not be separated by _syntactical_ _space_. A line break is a syntactical element, too. Every command argument can be followed by white‐ space, a comment, or a newline character. Thus a _syntactical_ _line_ _break_ is defined to con‐ sist of optional _syntactical_ _space_ that is optionally followed by a comment, and a newline character. The normal commands, those for positioning and text, consist of a single letter taking a fixed number of arguments. For historical reasons, the parser allows stacking of such com‐ mands on the same line, but fortunately, in _groff_ _intermediate_ _output_, every command with at least one argument is followed by a line break, thus providing excellent readability. The other commands — those for drawing and device controlling — have a more complicated structure; some recognize long command names, and some take a variable number of arguments. So all **D** and **x** commands were designed to request a _syntactical_ _line_ _break_ after their last argument. Only one command, ‘**x** **X**’ has an argument that can stretch over several lines, all other commands must have all of their arguments on the same line as the command, i.e., the arguments may not be split by a line break. Empty lines, i.e., lines containing only space and/or a comment, can occur everywhere. They are just ignored. ### Argument Units Some commands take integer arguments that are assumed to represent values in a measurement unit, but the letter for the corresponding _scale_ _indicator_ is not written with the output command arguments; see [**groff**(7)](https://www.chedong.com/phpMan.php/man/groff/7/markdown) and _Groff:_ _The_ _GNU_ _Implementation_ _of_ _troff_, the _groff_ Texinfo manual, for more on this topic. Most commands assume the scale indicator **u**, the basic unit of the device, some use **z**, the _scaled_ _point_ _unit_ of the device, while others, such as the color commands expect plain integers. Note that these scale indicators are relative to the chosen device. They are defined by the parameters specified in the device's _DESC_ file; see **groff**___**[font**(5)](https://www.chedong.com/phpMan.php/man/font/5/markdown). Note that single characters can have the eighth bit set, as can the names of fonts and spe‐ cial characters (this is, glyphs). The names of glyphs and fonts can be of arbitrary length. A glyph that is to be printed will always be in the current font. A string argument is always terminated by the next whitespace character (space, tab, or new‐ line); an embedded **#** character is regarded as part of the argument, not as the beginning of a comment command. An integer argument is already terminated by the next non-digit character, which then is regarded as the first character of the next argument or command. ### Document Parts A correct _intermediate_ _output_ document consists of two parts, the _prologue_ and the _body_. The task of the _prologue_ is to set the general device parameters using three exactly speci‐ fied commands. The _groff_ _prologue_ is guaranteed to consist of the following three lines (in that order): **x** **T** _device_ **x** **res** _n_ _h_ _v_ **x** **init** with the arguments set as outlined in subsection “Device Control Commands” below. However, the parser for the _intermediate_ _output_ format is able to swallow additional whitespace and comments as well. The _body_ is the main section for processing the document data. Syntactically, it is a se‐ quence of any commands different from the ones used in the _prologue_. Processing is termi‐ nated as soon as the first **x** **stop** command is encountered; the last line of any _groff_ _interme__‐ _diate_ _output_ always contains such a command. Semantically, the _body_ is page oriented. A new page is started by a **p** command. Positioning, writing, and drawing commands are always done within the current page, so they cannot occur before the first **p** command. Absolute positioning (by the **H** and **V** commands) is done relative to the current page, all other positioning is done relative to the current location within this page. ## COMMAND REFERENCE This section describes all _intermediate_ _output_ commands, the classical commands as well as the _groff_ extensions. ### Comment Command **#**_anything_⟨⟨**end-of-line**⟩⟩ A comment. Ignore any characters from the **#** character up to the next newline charac‐ ter. This command is the only possibility for commenting in the _intermediate_ _output_. Each comment can be preceded by arbitrary _syntactical_ _space_; every command can be terminated by a comment. ### Simple Commands The commands in this subsection have a command code consisting of a single character, taking a fixed number of arguments. Most of them are commands for positioning and text writing. These commands are smart about whitespace. Optionally, _syntactical_ _space_ can be inserted be‐ fore, after, and between the command letter and its arguments. All of these commands are stackable, i.e., they can be preceded by other simple commands or followed by arbitrary other commands on the same line. A separating _syntactical_ _space_ is only necessary when two integer arguments would clash or if the preceding argument ends with a string argument. **C** _xxx_⟨white-space⟩ Print a glyph (special character) named _xxx_. The trailing _syntactical_ _space_ or _line_ _break_ is necessary to allow glyph names of arbitrary length. The glyph is printed at the current print position; the glyph's size is read from the font file. The print position is not changed. **c** _c_ Print glyph with single-letter name _c_ at the current print position; the glyph's size is read from the font file. The print position is not changed. **f** _n_ Set font to font number _n_ (a non-negative integer). **H** _n_ Move right to the absolute vertical position _n_ (a non-negative integer in basic units **u**) relative to left edge of current page. **h** _n_ Move _n_ (a non-negative integer) basic units **u** horizontally to the right. [CSTR #54] allows negative values for _n_ also, but _groff_ doesn't use this. **m** _color-scheme_ [_component_ _..._] Set the color for text (glyphs), line drawing, and the outline of graphic objects us‐ ing different color schemes; the analogous command for the filling color of graphic objects is **DF**. The color components are specified as integer arguments between 0 and 65536. The number of color components and their meaning vary for the different color schemes. These commands are generated by the _groff_ escape sequence **\m**. No position changing. These commands are a _groff_ extension. **mc** _cyan_ _magenta_ _yellow_ Set color using the CMY color scheme, having the 3 color components cyan, ma‐ genta, and yellow. **md** Set color to the default color value (black in most cases). No component argu‐ ments. **mg** _gray_ Set color to the shade of gray given by the argument, an integer between 0 (black) and 65536 (white). **mk** _cyan_ _magenta_ _yellow_ _black_ Set color using the CMYK color scheme, having the 4 color components cyan, ma‐ genta, yellow, and black. **mr** _red_ _green_ _blue_ Set color using the RGB color scheme, having the 3 color components red, green, and blue. **N** _n_ Print glyph with index _n_ (an integer, normally non-negative) of the current font. The print position is not changed. If **-T** **html** or **-T** **xhtml** is used, negative values are emitted also to indicate an unbreakable space with given width. For example, **N** **-193** represents an unbreakable space which has a width of 193u. This command is a _groff_ extension. **n** _b_ _a_ Inform the device about a line break, but no positioning is done by this command. In _classical_ _troff_, the integer arguments _b_ and _a_ informed about the space before and af‐ ter the current line to make the _intermediate_ _output_ more human readable without per‐ forming any action. In _groff_, they are just ignored, but they must be provided for compatibility reasons. **p** _n_ Begin a new page in the outprint. The page number is set to _n_. This page is com‐ pletely independent of pages formerly processed even if those have the same page num‐ ber. The vertical position on the outprint is automatically set to 0. All position‐ ing, writing, and drawing is always done relative to a page, so a **p** command must be issued before any of these commands. **s** _n_ Set point size to _n_ scaled points (this is unit **z** in GNU **troff**). _Classical_ _troff_ used the unit _points_ (**p**) instead; see section “Compatibility” below. **t** _xyz..._⟨white-space⟩ **t** _xyz..._ _dummy-arg_⟨white-space⟩ Print a word, i.e., a sequence of glyphs with single-letter names _x_, _y_, _z_, etc., ter‐ minated by a space character or a line break; an optional second integer argument is ignored (this allows the formatter to generate an even number of arguments). The first glyph should be printed at the current position, the current horizontal position should then be increased by the width of the first glyph, and so on for each glyph. The widths of the glyph are read from the font file, scaled for the current point size, and rounded to a multiple of the horizontal resolution. Special characters (glyphs with names longer than a single letter) cannot be printed using this command; use the **C** command for those glyphs. This command is a _groff_ extension; it is only used for devices whose _DESC_ file contains the **tcommand** keyword; see **groff**___**[font**(5)](https://www.chedong.com/phpMan.php/man/font/5/markdown). **u** _n_ _xyz..._⟨white-space⟩ Print word with track kerning. This is the same as the **t** command except that after printing each glyph, the current horizontal position is increased by the sum of the width of that glyph and _n_ (an integer in basic units **u**). This command is a _groff_ ex‐ tension; it is only used for devices whose _DESC_ file contains the **tcommand** keyword; see **groff**___**[font**(5)](https://www.chedong.com/phpMan.php/man/font/5/markdown). **V** _n_ Move down to the absolute vertical position _n_ (a non-negative integer in basic units **u**) relative to upper edge of current page. **v** _n_ Move _n_ basic units **u** down (_n_ is a non-negative integer). [CSTR #54] allows negative values for _n_ also, but _groff_ doesn't use this. **w** Informs about a paddable whitespace to increase readability. The spacing itself must be performed explicitly by a move command. ### Graphics Commands Each graphics or drawing command in the _intermediate_ _output_ starts with the letter **D** followed by one or two characters that specify a subcommand; this is followed by a fixed or variable number of integer arguments that are separated by a single space character. A **D** command may not be followed by another command on the same line (apart from a comment), so each **D** command is terminated by a _syntactical_ _line_ _break_. **troff** output follows the classical spacing rules (no space between command and subcommand, all arguments are preceded by a single space character), but the parser allows optional space between the command letters and makes the space before the first argument optional. As usual, each space can be any sequence of tab and space characters. Some graphics commands can take a variable number of arguments. In this case, they are inte‐ gers representing a size measured in basic units **u**. The _h_ arguments stand for horizontal distances where positive means right, negative left. The _v_ arguments stand for vertical dis‐ tances where positive means down, negative up. All these distances are offsets relative to the current location. Unless indicated otherwise, each graphics command directly corresponds to a similar _groff_ **\D** escape sequence; see [**groff**(7)](https://www.chedong.com/phpMan.php/man/groff/7/markdown). Unknown **D** commands are assumed to be device-specific. Its arguments are parsed as strings; the whole information is then sent to the postprocessor. In the following command reference, the syntax element _⟨_line-break__⟩ means a _syntactical_ _line_ _break_ as defined in subsection “Separation” above. **D~** _h1_ _v1_ _h2_ _v2_ ... _hn_ _vn_⟨line-break⟩ Draw B-spline from current position to offset (_h1_, _v1_), then to offset (_h2_, _v2_) if given, etc., up to (_hn_, _vn_). This command takes a variable number of argument pairs; the current position is moved to the terminal point of the drawn curve. **Da** _h1_ _v1_ _h2_ _v2_⟨line-break⟩ Draw arc from current position to (_h1_, _v1_)+(_h2_, _v2_) with center at (_h1_, _v1_); then move the current position to the final point of the arc. **DC** _d_⟨line-break⟩ **DC** _d_ _dummy-arg_⟨line-break⟩ Draw a solid circle using the current fill color with diameter _d_ (integer in basic units **u**) with leftmost point at the current position; then move the current position to the rightmost point of the circle. An optional second integer argument is ignored (this allows the formatter to generate an even number of arguments). This command is a _groff_ extension. **Dc** _d_⟨line-break⟩ Draw circle line with diameter _d_ (integer in basic units **u**) with leftmost point at the current position; then move the current position to the rightmost point of the circle. **DE** _h_ _v_⟨line-break⟩ Draw a solid ellipse in the current fill color with a horizontal diameter of _h_ and a vertical diameter of _v_ (both integers in basic units **u**) with the leftmost point at the current position; then move to the rightmost point of the ellipse. This command is a _groff_ extension. **De** _h_ _v_⟨line-break⟩ Draw an outlined ellipse with a horizontal diameter of _h_ and a vertical diameter of _v_ (both integers in basic units **u**) with the leftmost point at current position; then move to the rightmost point of the ellipse. **DF** _color-scheme_ [_component_ _..._]⟨line-break⟩ Set fill color for solid drawing objects using different color schemes; the analogous command for setting the color of text, line graphics, and the outline of graphic ob‐ jects is **m**. The color components are specified as integer arguments between 0 and 65536. The number of color components and their meaning vary for the different color schemes. These commands are generated by the _groff_ escape sequences **\D'F** ...**'** and **\M** (with no other corresponding graphics commands). No position changing. This command is a _groff_ extension. **DFc** _cyan_ _magenta_ _yellow_⟨line-break⟩ Set fill color for solid drawing objects using the CMY color scheme, having the 3 color components cyan, magenta, and yellow. **DFd** ⟨line-break⟩ Set fill color for solid drawing objects to the default fill color value (black in most cases). No component arguments. **DFg** _gray_⟨line-break⟩ Set fill color for solid drawing objects to the shade of gray given by the ar‐ gument, an integer between 0 (black) and 65536 (white). **DFk** _cyan_ _magenta_ _yellow_ _black_⟨line-break⟩ Set fill color for solid drawing objects using the CMYK color scheme, having the 4 color components cyan, magenta, yellow, and black. **DFr** _red_ _green_ _blue_⟨line-break⟩ Set fill color for solid drawing objects using the RGB color scheme, having the 3 color components red, green, and blue. **Df** _n_⟨line-break⟩ The argument _n_ must be an integer in the range -32767 to 32767. 0≤_n_≤1000 Set the color for filling solid drawing objects to a shade of gray, where 0 corresponds to solid white, 1000 (the default) to solid black, and values in between to intermediate shades of gray; this is obsoleted by command **DFg**. _n_<0 or _n_>1000 Set the filling color to the color that is currently being used for the text and the outline, see command **m**. For example, the command sequence mg 0 0 65536 Df -1 sets all colors to blue. No position changing. This command is a _groff_ extension. **Dl** _h_ _v_⟨line-break⟩ Draw line from current position to offset (_h_, _v_) (integers in basic units **u**); then set current position to the end of the drawn line. **Dp** _h1_ _v1_ _h2_ _v2_ ... _hn_ _vn_⟨line-break⟩ Draw a polygon line from current position to offset (_h1_, _v1_), from there to offset (_h2_, _v2_), etc., up to offset (_hn_, _vn_), and from there back to the starting position. For historical reasons, the position is changed by adding the sum of all arguments with odd index to the actual horizontal position and the even ones to the vertical po‐ sition. Although this doesn't make sense it is kept for compatibility. This command is a _groff_ extension. **DP** _h1_ _v1_ _h2_ _v2_ ... _hn_ _vn_⟨line-break⟩ The same macro as the corresponding **Dp** command with the same arguments, but draws a solid polygon in the current fill color rather than an outlined polygon. The position is changed in the same way as with **Dp**. This command is a _groff_ extension. **Dt** _n_⟨line-break⟩ Set the current line thickness to _n_ (an integer in basic units **u**) if _n_>0; if _n_=0 se‐ lect the smallest available line thickness; if _n_<0 set the line thickness proportional to the point size (this is the default before the first **Dt** command was specified). For historical reasons, the horizontal position is changed by adding the argument to the actual horizontal position, while the vertical position is not changed. Although this doesn't make sense it is kept for compatibility. This command is a _groff_ exten‐ sion. ### Device Control Commands Each device control command starts with the letter **x** followed by a space character (optional or arbitrary space/tab in _groff_) and a subcommand letter or word; each argument (if any) must be preceded by a _syntactical_ _space_. All **x** commands are terminated by a _syntactical_ _line_ _break_; no device control command can be followed by another command on the same line (except a comment). The subcommand is basically a single letter, but to increase readability, it can be written as a word, i.e., an arbitrary sequence of characters terminated by the next tab, space, or newline character. All characters of the subcommand word but the first are simply ignored. For example, **troff** outputs the initialization command **x** **i** as **x** **init** and the resolution com‐ mand **x** **r** as **x** **res**. But writings like **x** **i**___**like**___**groff** and **x** **roff**___**is**___**groff** are accepted as well to mean the same commands. In the following, the syntax element _⟨_line-break__⟩ means a _syntactical_ _line_ _break_ as defined in subsection “Separation” above. **xF** _name_⟨line-break⟩ (_Filename_ control command) Use _name_ as the intended name for the current file in error reports. This is useful for remembering the original file name when **groff** uses an internal piping mechanism. The input file is not changed by this command. This command is a _groff_ extension. **xf** _n_ _s_⟨line-break⟩ (_font_ control command) Mount font position _n_ (a non-negative integer) with font named _s_ (a text word); see **groff**___**[font**(5)](https://www.chedong.com/phpMan.php/man/font/5/markdown). **xH** _n_⟨line-break⟩ (_Height_ control command) Set character height to _n_ (a positive integer in scaled points **z**). _Classical_ _troff_ used the unit points (**p**) instead; see section “Compatibility” below. **xi** ⟨line-break⟩ (_init_ control command) Initialize device. This is the third command of the _prologue_. **xp** ⟨line-break⟩ (_pause_ control command) Parsed but ignored. The classical documentation reads _pause_ _device,_ _can_ _be_ _restarted_. **xr** _n_ _h_ _v_⟨line-break⟩ (_resolution_ control command) Resolution is _n_, while _h_ is the minimal horizontal motion, and _v_ the minimal vertical motion possible with this device; all arguments are positive integers in basic units **u** per inch. This is the second command of the _prologue_. **xS** _n_⟨line-break⟩ (_Slant_ control command) Set slant to _n_ degrees (an integer in basic units **u**). **xs** ⟨line-break⟩ (_stop_ control command) Terminates the processing of the current file; issued as the last command of any _in__‐ _termediate_ _troff_ _output_. **xt** ⟨line-break⟩ (_trailer_ control command) Generate trailer information, if any. In **groff**, this is actually just ignored. **xT** _xxx_⟨line-break⟩ (_Typesetter_ control command) Set name of device to word _xxx_, a sequence of characters ended by the next whitespace character. The possible device names coincide with those from the groff **-T** option. This is the first command of the _prologue_. **xu** _n_⟨line-break⟩ (_underline_ control command) Configure underlining of spaces. If _n_ is 1, start underlining of spaces; if _n_ is 0, stop underlining of spaces. This is needed for the **cu** request in **nroff** mode and is ignored otherwise. This command is a _groff_ extension. **xX** _anything_⟨line-break⟩ (_X-escape_ control command) Send string _anything_ uninterpreted to the device. If the line following this command starts with a **+** character this line is interpreted as a continuation line in the fol‐ lowing sense. The **+** is ignored, but a newline character is sent instead to the de‐ vice, the rest of the line is sent uninterpreted. The same applies to all following lines until the first character of a line is not a **+** character. This command is gen‐ erated by the _groff_ escape sequence **\X**. The line-continuing feature is a _groff_ exten‐ sion. ### Obsolete Command In _classical_ _troff_ output, emitting a single glyph was mostly done by a very strange command that combined a horizontal move and the printing of a glyph. It didn't have a command code, but is represented by a 3-character argument consisting of exactly 2 digits and a character. _ddc_ Move right _dd_ (exactly two decimal digits) basic units **u**, then print glyph with sin‐ gle-letter name _c_. In _groff_, arbitrary _syntactical_ _space_ around and within this command is allowed to be added. Only when a preceding command on the same line ends with an argument of vari‐ able length a separating space is obligatory. In _classical_ _troff_, large clusters of these and other commands were used, mostly without spaces; this made such output al‐ most unreadable. For modern high-resolution devices, this command does not make sense because the width of the glyphs can become much larger than two decimal digits. In **groff**, this is only used for the devices **X75**, **X75-12**, **X100**, and **X100-12**. For other devices, the commands **t** and **u** provide a better functionality. ## POSTPROCESSING The _roff_ postprocessors are programs that have the task to translate the _intermediate_ _output_ into actions that are sent to a device. A device can be some piece of hardware such as a printer, or a software file format suitable for graphical or text processing. The _groff_ sys‐ tem provides powerful means that make the programming of such postprocessors an easy task. There is a library function that parses the _intermediate_ _output_ and sends the information ob‐ tained to the device via methods of a class with a common interface for each device. So a _groff_ postprocessor must only redefine the methods of this class. For details, see the ref‐ erence in section “Files” below. ## EXAMPLES This section presents the _intermediate_ _output_ generated from the same input for three differ‐ ent devices. The input is the sentence _hell_ _world_ fed into **groff** on the command line. • High-resolution device _ps_ **shell>** echo "hell world" | groff -Z -T ps **x** **T** **ps** **x** **res** **72000** **1** **1** **x** **init** **p1** **x** **font** **5** **TR** **f5** **s10000** **V12000** **H72000** **thell** **wh2500** **tw** **H96620** **torld** **n12000** **0** **x** **trailer** **V792000** **x** **stop** This output can be fed into the postprocessor [**grops**(1)](https://www.chedong.com/phpMan.php/man/grops/1/markdown) to get its representation as a Post‐ Script file, or [**gropdf**(1)](https://www.chedong.com/phpMan.php/man/gropdf/1/markdown) to output directly to PDF. • Low-resolution device _latin1_ This is similar to the high-resolution device except that the positioning is done at a mi‐ nor scale. Some comments (lines starting with _#_) were added for clarification; they were not generated by the formatter. **shell>** "hell world" | groff -Z -T latin1 _#_ _prologue_ **x** **T** **latin1** **x** **res** **240** **24** **40** **x** **init** _#_ _begin_ _a_ _new_ _page_ **p1** _#_ _font_ _setup_ **x** **font** **1** **R** **f1** **s10** _#_ _initial_ _positioning_ _on_ _the_ _page_ **V40** **H0** _#_ _write_ _text_ _‘_hell__’ **thell** _#_ _inform_ _about_ _a_ _space,_ _and_ _do_ _it_ _by_ _a_ _horizontal_ _jump_ **wh24** _#_ _write_ _text_ _‘_world__’ **tworld** _#_ _announce_ _line_ _break,_ _but_ _do_ _nothing_ _because_ _..._ **n40** **0** _#_ _..._ _the_ _end_ _of_ _the_ _document_ _has_ _been_ _reached_ **x** **trailer** **V2640** **x** **stop** This output can be fed into the postprocessor [**grotty**(1)](https://www.chedong.com/phpMan.php/man/grotty/1/markdown) to get a formatted text document. • Classical style output As a computer monitor has a very low resolution compared to modern printers the _intermedi__‐ _ate_ _output_ for the X devices can use the jump-and-write command with its 2-digit displace‐ ments. **shell>** "hell world" | groff -Z -T X100 **x** **T** **X100** **x** **res** **100** **1** **1** **x** **init** **p1** **x** **font** **5** **TR** **f5** **s10** **V16** **H100** _#_ _write_ _text_ _with_ _old-style_ _jump-and-write_ _command_ **ch07e07l03lw06w11o07r05l03dh7** **n16** **0** **x** **trailer** **V1100** **x** **stop** This output can be fed into the postprocessor [**xditview**(1x)](https://www.chedong.com/phpMan.php/man/xditview/1x/markdown) or [**gxditview**(1)](https://www.chedong.com/phpMan.php/man/gxditview/1/markdown) for displaying in X. Due to the obsolete jump-and-write command, the text clusters in the classical output are al‐ most unreadable. ## COMPATIBILITY The _intermediate_ _output_ language of the _classical_ _troff_ was first documented in [CSTR #97] . The _groff_ _intermediate_ _output_ format is compatible with this specification except for the following features. • The classical quasi device independence is not yet implemented. • The old hardware was very different from what we use today. So the _groff_ devices are also fundamentally different from the ones in _classical_ _troff_. For example, the classical Post‐ Script device was called _post_ and had a resolution of 720 units per inch, while _groff_'s _ps_ device has a resolution of 72000 units per inch. Maybe, by implementing some rescaling mechanism similar to the classical quasi device independence, these could be integrated into modern _groff_. • The B-spline command **D~** is correctly handled by the _intermediate_ _output_ parser, but the drawing routines aren't implemented in some of the postprocessor programs. • The argument of the commands **s** and **x** **H** has the implicit unit scaled point **z** in _groff_, while _classical_ _troff_ had point (**p**). This isn't an incompatibility, but a compatible extension, for both units coincide for all devices without a _sizescale_ parameter, including all clas‐ sical and the _groff_ text devices. The few _groff_ devices with a sizescale parameter either did not exist, had a different name, or seem to have had a different resolution. So con‐ flicts with classical devices are very unlikely. • The position changing after the commands **Dp**, **DP**, and **Dt** is illogical, but as old versions of groff used this feature it is kept for compatibility reasons. The differences between _groff_ and _classical_ _troff_ are documented in **groff**___**[diff**(7)](https://www.chedong.com/phpMan.php/man/diff/7/markdown). ## FILES _/usr/share/groff/1.22.4/font/dev_name_/DESC_ Device description file for device _name_. _src/libs/libdriver/input.cpp_ Defines the parser and postprocessor for the _intermediate_ _output_. It is located rela‐ tive to the top directory of the _groff_ source tree. This parser is the definitive specification of the _groff_ _intermediate_ _output_ format. ## AUTHORS James Clark wrote an early version of this document, which described only the differences be‐ tween [**ditroff**(7)](https://www.chedong.com/phpMan.php/man/ditroff/7/markdown)'s output format and that of GNU _roff_. The present version was completely rewritten in 2001 by Bernd Warken ⟨⟩. ## SEE ALSO A reference like [**groff**(7)](https://www.chedong.com/phpMan.php/man/groff/7/markdown) refers to a manual page; here **groff** in section _7_ of the man page documentation system. To read the example, look up section 7 in your desktop help system or call from the shell prompt **shell>** man 7 groff For more details, see [**man**(1)](https://www.chedong.com/phpMan.php/man/man/1/markdown). [**groff**(1)](https://www.chedong.com/phpMan.php/man/groff/1/markdown) option **-Z** and further readings on groff. [**groff**(7)](https://www.chedong.com/phpMan.php/man/groff/7/markdown) for details of the _groff_ language such as numerical units and escape sequences. **groff**___**[font**(5)](https://www.chedong.com/phpMan.php/man/font/5/markdown) for details on the device scaling parameters of the _DESC_ file. [**troff**(1)](https://www.chedong.com/phpMan.php/man/troff/1/markdown) generates the device-independent intermediate output. [**roff**(7)](https://www.chedong.com/phpMan.php/man/roff/7/markdown) for historical aspects and the general structure of roff systems. **groff**___**[diff**(7)](https://www.chedong.com/phpMan.php/man/diff/7/markdown) The differences between the intermediate output in groff and classical troff. [**gxditview**(1)](https://www.chedong.com/phpMan.php/man/gxditview/1/markdown) Viewer for the _intermediate_ _output_. [**grodvi**(1)](https://www.chedong.com/phpMan.php/man/grodvi/1/markdown), [**grohtml**(1)](https://www.chedong.com/phpMan.php/man/grohtml/1/markdown), [**grolbp**(1)](https://www.chedong.com/phpMan.php/man/grolbp/1/markdown), [**grolj4**(1)](https://www.chedong.com/phpMan.php/man/grolj4/1/markdown), [**grops**(1)](https://www.chedong.com/phpMan.php/man/grops/1/markdown), [**grotty**(1)](https://www.chedong.com/phpMan.php/man/grotty/1/markdown) the groff postprocessor programs. _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”. The _classical_ _troff_ _output_ _language_ is described in two AT&T Bell Labs CSTR documents avail‐ able on-line at Bell Labs CSTR site ⟨⟩. [CSTR #97] _A_ _Typesetter-independent_ _TROFF_ by _Brian_ _Kernighan_ is the original and most comprehen‐ sive documentation on the output language; see CSTR #97 ⟨ cs/cstr/97.ps.gz⟩. [CSTR #54] The 1992 revision of the _Nroff/Troff_ _User's_ _Manual_ by _J._ _F._ _Ossanna_ and _Brian_ _Kernighan_ isn't as comprehensive as [CSTR #97] regarding the output language; see CSTR #54 ⟨⟩. groff 1.22.4 23 March 2022 [GROFF_OUT(5)](https://www.chedong.com/phpMan.php/man/GROFFOUT/5/markdown)