This is groff, produced by makeinfo version 4.2 from ./groff.texinfo. This manual documents GNU `troff' version 1.18. Copyright (C) 1994-2000, 2001, 2002 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover texts being `A GNU Manual," and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled `GNU Free Documentation License." (a) The FSF's Back-Cover Text is: `You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development." INFO-DIR-SECTION Miscellaneous START-INFO-DIR-ENTRY * Groff: (groff). The GNU troff document formatting system. END-INFO-DIR-ENTRY  File: groff, Node: grops, Next: grodvi, Prev: grotty, Up: Output Devices `grops' ======= * Menu: * Invoking grops:: * Embedding PostScript::  File: groff, Node: Invoking grops, Next: Embedding PostScript, Prev: grops, Up: grops Invoking `grops' ----------------  File: groff, Node: Embedding PostScript, Prev: Invoking grops, Up: grops Embedding POSTSCRIPT --------------------  File: groff, Node: grodvi, Next: grolj4, Prev: grops, Up: Output Devices `grodvi' ======== * Menu: * Invoking grodvi::  File: groff, Node: Invoking grodvi, Prev: grodvi, Up: grodvi Invoking `grodvi' -----------------  File: groff, Node: grolj4, Next: grolbp, Prev: grodvi, Up: Output Devices `grolj4' ======== * Menu: * Invoking grolj4::  File: groff, Node: Invoking grolj4, Prev: grolj4, Up: grolj4 Invoking `grolj4' -----------------  File: groff, Node: grolbp, Next: grohtml, Prev: grolj4, Up: Output Devices `grolbp' ======== * Menu: * Invoking grolbp::  File: groff, Node: Invoking grolbp, Prev: grolbp, Up: grolbp Invoking `grolbp' -----------------  File: groff, Node: grohtml, Next: gxditview, Prev: grolbp, Up: Output Devices `grohtml' ========= * Menu: * Invoking grohtml:: * grohtml specific registers and strings::  File: groff, Node: Invoking grohtml, Next: grohtml specific registers and strings, Prev: grohtml, Up: grohtml Invoking `grohtml' ------------------  File: groff, Node: grohtml specific registers and strings, Prev: Invoking grohtml, Up: grohtml `grohtml' specific registers and strings ---------------------------------------- - Register: \n[ps4html] - String: \*[www-image-template] The registers `ps4html' and `www-image-template' are defined by the `pre-grohtml' preprocessor. `pre-grohtml' reads in the `troff' input, marks up the inline equations and passes the result firstly to troff -Tps -rps4html=1 -dwww-image-template=TEMPLATE and secondly to troff -Thtml The PostScript device is used to create all the image files, and the register `ps4html' enables the macro sets to ignore floating keeps, footers, and headings. The register `www-image-template' is set to the user specified template name or the default name.  File: groff, Node: gxditview, Prev: grohtml, Up: Output Devices `gxditview' =========== * Menu: * Invoking gxditview::  File: groff, Node: Invoking gxditview, Prev: gxditview, Up: gxditview Invoking `gxditview' --------------------  File: groff, Node: File formats, Next: Installation, Prev: Output Devices, Up: Top File formats ************ All files read and written by `gtroff' are text files. The following two sections describe their format. * Menu: * gtroff Output:: * Font Files::  File: groff, Node: gtroff Output, Next: Font Files, Prev: File formats, Up: File formats `gtroff' Output =============== This section describes the intermediate output format of GNU `troff'. This output is produced by a run of `gtroff' before it is fed into a device postprocessor program. As `groff' is a wrapper program around `gtroff' that automatically calls a postprocessor, this output does not show up normally. This is why it is called "intermediate". `groff' provides the option `-Z' to inhibit postprocessing, such that the produced intermediate output is sent to standard output just like calling `gtroff' manually. Here, the term "troff output" describes what is output by `gtroff', 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 obsolete elements for compatibility, otherwise both formats are the same.(1) (*note gtroff Output-Footnote-1::) The main purpose of the intermediate output concept is to facilitate the development of postprocessors by providing a common programming interface for all devices. It has a language of its own that is completely different from the `gtroff' language. While the `gtroff' 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 intermediate output produced by `gtroff' is fairly readable, while output from AT&T `troff' is rather hard to understand because of strange habits that are still supported, but not used any longer by `gtroff'. * Menu: * Language Concepts:: * Command Reference:: * Intermediate Output Examples:: * Output Language Compatibility::  File: groff, Node: gtroff Output-Footnotes, Up: gtroff Output (1) The parser and postprocessor for intermediate output can be found in the file `GROFF-SOURCE-DIR/src/libs/libdriver/input.cc'.  File: groff, Node: Language Concepts, Next: Command Reference, Prev: gtroff Output, Up: gtroff Output Language Concepts ----------------- During the run of `gtroff', the input data 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 and without arguments. In this section, the term "command" always refers to the intermediate output language, and never to the `gtroff' language used for document formatting. There are commands for positioning and text writing, for drawing, and for device controlling. * Menu: * Separation:: * Argument Units:: * Document Parts::  File: groff, Node: Separation, Next: Argument Units, Prev: Language Concepts, Up: Language Concepts Separation .......... AT&T `troff' output has strange requirements on whitespace. The `gtroff' output parser, however, 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 separates 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 arguments 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 whitespace, a comment, or a newline character. Thus a "syntactical line break" is defined to consist 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 to stack such commands on the same line, but fortunately, in `gtroff''s 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 splitted by a line break. Empty lines (these are lines containing only space and/or a comment), can occur everywhere. They are just ignored.  File: groff, Node: Argument Units, Next: Document Parts, Prev: Separation, Up: Language Concepts 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. 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 single characters can have the eighth bit set, as can the names of fonts and special characters. The names of characters and fonts can be of arbitrary length. A character 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 newline); 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.  File: groff, Node: Document Parts, Prev: Argument Units, Up: Language Concepts 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 specified commands. `gtroff''s 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 *Note Device Control Commands::. Note that the parser for the intermediate output format is able to swallow additional whitespace and comments as well even in the prologue. The body is the main section for processing the document data. Syntactically, it is a sequence of any commands different from the ones used in the prologue. Processing is terminated as soon as the first `x stop' command is encountered; the last line of any `gtroff' intermediate 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.  File: groff, Node: Command Reference, Next: Intermediate Output Examples, Prev: Language Concepts, Up: gtroff Output Command Reference ----------------- This section describes all intermediate output commands, both from AT&T `troff' as well as the `gtroff' extensions. * Menu: * Comment Command:: * Simple Commands:: * Graphics Commands:: * Device Control Commands:: * Obsolete Command::  File: groff, Node: Comment Command, Next: Simple Commands, Prev: Command Reference, Up: Command Reference Comment Command ............... `#ANYTHING' A comment. Ignore any characters from the `#' character up to the next newline character. 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.  File: groff, Node: Simple Commands, Next: Graphics Commands, Prev: Comment Command, Up: Command Reference 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 before, 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' Print a 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 G' Print glyph G at the current print position;(1) (*note Simple Commands-Footnote-1::) 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. The original UNIX troff manual allows negative values for N also, but `gtroff' doesn't use this. `m COLOR-SCHEME [COMPONENT ...]' Set the color for text (glyphs), line drawing, and the outline of graphic objects using different color schemes; the analoguous 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 `gtroff''s escape sequence `\m'. No position changing. These commands are a `gtroff' extension. `mc CYAN MAGENTA YELLOW' Set color using the CMY color scheme, having the 3 color components CYAN, MAGENTA, and YELLOW. `md' Set color to the default color value (black in most cases). No component arguments. `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, MAGENTA, 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 (a non-negative integer) of the current font. This command is a `gtroff' extension. `n B A' Inform the device about a line break, but no positioning is done by this command. In AT&T `troff', the integer arguments B and A informed about the space before and after the current line to make the intermediate output more human readable without performing 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 completely independent of pages formerly processed even if those have the same page number. The vertical position on the outprint is automatically set to 0. All positioning, 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'). AT&T `troff' used the unit points (`p') instead. *Note Output Language Compatibility::. `t XXX' `t XXX DUMMY-ARG' Print a word, i.e., a sequence of characters XXX representing output glyphs which names are single characters, terminated 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 glyphs are read from the font file, scaled for the current point size, and rounded to a multiple of the horizontal resolution. Special characters cannot be printed using this command (use the `C' command for special characters). This command is a `gtroff' extension; it is only used for devices whose `DESC' file contains the `tcommand' keyword (*note DESC File Format::). `u N XXX' 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 `gtroff' extension; it is only used for devices whose `DESC' file contains the `tcommand' keyword (*note DESC File Format::). `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). The original UNIX troff manual allows negative values for N also, but `gtroff' doesn't use this. `w' Informs about a paddable white space to increase readability. The spacing itself must be performed explicitly by a move command.  File: groff, Node: Simple Commands-Footnotes, Up: Simple Commands (1) `c' is actually a misnomer since it outputs a glyph.  File: groff, Node: Graphics Commands, Next: Device Control Commands, Prev: Simple Commands, Up: Command Reference 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. `gtroff' 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 integers representing a size measured in basic units `u'. The arguments called H1, H2, ..., HN stand for horizontal distances where positive means right, negative left. The arguments called V1, V2, ..., VN stand for vertical distances 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 `gtroff' `\D' escape sequence. *Note Drawing Requests::. 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 means a syntactical line break as defined above. `D~ H1 V1 H2 V2 ... HN VN' 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' 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' `DC D DUMMY-ARG' 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 `gtroff' extension. `Dc D' 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' 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 `gtroff' extension. `De H V' 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 ...]' Set fill color for solid drawing objects using different color schemes; the analoguous command for setting the color of text, line graphics, and the outline of graphic objects 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 `gtroff''s escape sequences `\D'F ...'' and `\M' (with no other corresponding graphics commands). No position changing. This command is a `gtroff' extension. `DFc CYAN MAGENTA YELLOW' Set fill color for solid drawing objects using the CMY color scheme, having the 3 color components CYAN, MAGENTA, and YELLOW. `DFd' Set fill color for solid drawing objects to the default fill color value (black in most cases). No component arguments. `DFg GRAY' Set fill color for solid drawing objects to the shade of gray given by the argument, an integer between 0 (black) and 65536 (white). `DFk CYAN MAGENTA YELLOW BLACK' 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' Set fill color for solid drawing objects using the RGB color scheme, having the 3 color components RED, GREEN, and BLUE. `Df N' 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 `gtroff' extension. `Dl H V' 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' 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 position. Although this doesn't make sense it is kept for compatibility. This command is a `gtroff' extension. `Dp H1 V1 H2 V2 ... HN VN' Draw a solid polygon in the current fill color rather than an outlined polygon, using the same arguments and positioning as the corresponding `Dp' command. This command is a `gtroff' extension. `Dt N' Set the current line thickness to N (an integer in basic units `u') if N>0; if N=0 select 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 `gtroff' extension.  File: groff, Node: Device Control Commands, Next: Obsolete Command, Prev: Graphics Commands, Up: Command Reference Device Control Commands ....................... Each device control command starts with the letter `x', followed by a space character (optional or arbitrary space or tab in `gtroff') 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, `gtroff' outputs the initialization command `x i' as `x init' and the resolution command `x r' as `x res'. In the following, the syntax element means a syntactical line break (*note Separation::). `xF NAME' The `F' stands for FILENAME. Use NAME as the intended name for the current file in error reports. This is useful for remembering the original file name when `gtroff' uses an internal piping mechanism. The input file is not changed by this command. This command is a `gtroff' extension. `xf N S' The `f' stands for FONT. Mount font position N (a non-negative integer) with font named S (a text word). *Note Font Positions::. `xH N' The `H' stands for HEIGHT. Set glyph height to N (a positive integer in scaled points `z'). AT&T `troff' uses the unit points (`p') instead. *Note Output Language Compatibility::. `xi' The `i' stands for INIT. Initialize device. This is the third command of the prologue. `xp' The `p' stands for PAUSE. Parsed but ignored. The original UNIX troff manual writes pause device, can be restarted `xr N H V' The `r' stands for RESOLUTION. 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' The `S' stands for SLANT. Set slant to N (an integer in basic units `u'). `xs' The `s' stands for STOP. Terminates the processing of the current file; issued as the last command of any intermediate troff output. `xt' The `t' stands for TRAILER. Generate trailer information, if any. In GTROFF, this is actually just ignored. `xT XXX' The `T' stands for TYPESETTER. Set name of device to word XXX, a sequence of characters ended by the next white space character. The possible device names coincide with those from the `groff' `-T' option. This is the first command of the prologue. `xu N' The `u' stands for UNDERLINE. 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 `gtroff' extension. `xX ANYTHING' The `x' stands for X-ESCAPE. 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 following sense. The `+' is ignored, but a newline character is sent instead to the device, 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 generated by the `gtroff' escape sequence `\X'. The line-continuing feature is a `gtroff' extension.  File: groff, Node: Obsolete Command, Prev: Device Control Commands, Up: Command Reference Obsolete Command ................ In AT&T `troff' output, the writing of a single glyph is mostly done by a very strange command that combines a horizontal move and a single character giving the glyph name. It doesn't have a command code, but is represented by a 3-character argument consisting of exactly 2 digits and a character. DDG Move right DD (exactly two decimal digits) basic units `u', then print glyph G (represented as a single character). In `gtroff', 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 variable length a separating space is obligatory. In AT&T `troff', large clusters of these and other commands are used, mostly without spaces; this made such output almost 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 `gtroff', 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.  File: groff, Node: Intermediate Output Examples, Next: Output Language Compatibility, Prev: Command Reference, Up: gtroff Output Intermediate Output Examples ---------------------------- This section presents the intermediate output generated from the same input for three different devices. The input is the sentence `hell world' fed into `gtroff' on the command line. High-resolution device `ps' This is the standard output of `gtroff' if no `-T' option is given. 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 `grops' to get its representation as a PostScript file. Low-resolution device `latin1' This is similar to the high-resolution device except that the positioning is done at a minor scale. Some comments (lines starting with `#') were added for clarification; they were not generated by the formatter. shell> echo "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 space, and issue 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 `grotty' to get a formatted text document. AT&T `troff' output Since a computer monitor has a very low resolution compared to modern printers the intermediate output for the X Window devices can use the jump-and-write command with its 2-digit displacements. shell> echo "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 jump-and-write commands ch07e07l03lw06w11o07r05l03dh7 n16 0 x trailer V1100 x stop This output can be fed into `xditview' or `gxditview' for displaying in X. Due to the obsolete jump-and-write command, the text clusters in the AT&T `troff' output are almost unreadable.  File: groff, Node: Output Language Compatibility, Prev: Intermediate Output Examples, Up: gtroff Output Output Language Compatibility ----------------------------- The intermediate output language of AT&T `troff' was first documented in the UNIX troff manual, with later additions documented in `A Typesetter-indenpendent TROFF', written by Brian Kernighan. The `gtroff' 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 AT&T `troff'. For example, the AT&T PostScript device is called `post' and has a resolution of only 720 units per inch, suitable for printers 20 years ago, 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, `groff' could emulate AT&T's `post' device. * 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 `gtroff', while AT&T `troff' has point (`p'). This isn't an incompatibility but a compatible extension, for both units coincide for all devices without a `sizescale' parameter in the `DESC' file, including all postprocessors from AT&T and `groff''s text devices. The few `groff' devices with a `sizescale' parameter either do not exist for AT&T `troff', have a different name, or seem to have a different resolution. So conflicts are very unlikely. * The position changing after the commands `Dp', `DP', and `Dt' is illogical, but as old versions of `gtroff' used this feature it is kept for compatibility reasons.  File: groff, Node: Font Files, Prev: gtroff Output, Up: File formats Font Files ========== The `gtroff' font format is roughly a superset of the `ditroff' font format (as used in later versions of AT&T `troff' and its descendants). Unlike the `ditroff' font format, there is no associated binary format; all files are text files.(1) (*note Font Files-Footnote-1::) The font files for device NAME are stored in a directory `devNAME'. There are two types of file: a device description file called `DESC' and for each font F a font file called `F'. * Menu: * DESC File Format:: * Font File Format::  File: groff, Node: Font Files-Footnotes, Up: Font Files (1) Plan 9 `troff' has also abandoned the binary format.  File: groff, Node: DESC File Format, Next: Font File Format, Prev: Font Files, Up: Font Files `DESC' File Format ------------------ The `DESC' file can contain the following types of line. Except for the `charset' keyword which must comes last (if at all), the order of the lines is not important. `res N' There are N machine units per inch. `hor N' The horizontal resolution is N machine units. `vert N' The vertical resolution is N machine units. `sizescale N' The scale factor for point sizes. By default this has a value of 1. One scaled point is equal to one point/N. The arguments to the `unitwidth' and `sizes' commands are given in scaled points. *Note Fractional Type Sizes::, for more information. `unitwidth N' Quantities in the font files are given in machine units for fonts whose point size is N scaled points. `prepro PROGRAM' Call PROGRAM as a preprocessor. Currently, this keyword is used by `groff' with option `-Thtml' only. `postpro PROGRAM' Call PROGRAM as a postprocessor. For example, the line postpro grodvi in the file `devdvi/DESC' makes `groff' call `grodvi' if option `-Tdvi' is given (and `-Z' isn't used). `tcommand' This means that the postprocessor can handle the `t' and `u' intermediate output commands. `sizes S1 S2 ... SN 0' This means that the device has fonts at S1, S2, ... SN scaled points. The list of sizes must be terminated by 0 (this is digit zero). Each SI can also be a range of sizes M-N. The list can extend over more than one line. `styles S1 S2 ... SM' The first M font positions are associated with styles S1 ... SM. `fonts N F1 F2 F3 ... FN' Fonts F1 ... FN are mounted in the font positions M+1, ..., M+N where M is the number of styles. This command may extend over more than one line. A font name of 0 means no font is mounted on the corresponding font position. `family FAM' The default font family is FAM. `use_charnames_in_special' This command indicates that `gtroff' should encode special characters inside special commands. Currently, this is only used by the HTML output device. *Note Postprocessor Access::. `papersize STRING ...' Select a paper size. Valid values for STRING are the ISO paper types `A0'-`A7', `B0'-`B7', `C0'-`C7', `D0'-`D7', `DL', and the US paper types `letter', `legal', `tabloid', `ledger', `statement', `executive', `com10', and `monarch'. Case is not significant for STRING if it holds predefined paper types. Alternatively, STRING can be a file name (e.g. `/etc/papersize'); if the file can be opened, `groff' reads the first line and tests for the above paper sizes. Finally, STRING can be a custom paper size in the format `LENGTH,WIDTH' (no spaces before and after the comma). Both LENGTH and WIDTH must have a unit appended; valid values are `i' for inches, `C' for centimeters, `p' for points, and `P' for picas. Example: `12c,235p'. An argument which starts with a digit is always treated as a custom paper format. `papersize' sets both the vertical and horizontal dimension of the output medium. More than one argument can be specified; `groff' scans from left to right and uses the first valid paper specification. `pass_filenames' Tell `gtroff' to emit the name of the source file currently being processed. This is achieved by the intermediate output command `F'. Currently, this is only used by the HTML output device. `print PROGRAM' Use PROGRAM as a spooler program for printing. If omitted, the `-l' and `-L' options of `groff' are ignored. `charset' This line and everything following in the file are ignored. It is allowed for the sake of backwards compatibility. The `res', `unitwidth', `fonts', and `sizes' lines are mandatory. Other commands are ignored by `gtroff' but may be used by postprocessors to store arbitrary information about the device in the `DESC' file. Here a list of obsolete keywords which are recognized by `groff' but completely ignored: `spare1', `spare2', `biggestfont'.  File: groff, Node: Font File Format, Prev: DESC File Format, Up: Font Files Font File Format ---------------- A "font file", also (and probably better) called a "font description file", has two sections. The first section is a sequence of lines each containing a sequence of blank delimited words; the first word in the line is a key, and subsequent words give a value for that key. `name F' The name of the font is F. `spacewidth N' The normal width of a space is N. `slant N' The glyphs of the font have a slant of N degrees. (Positive means forward.) `ligatures LIG1 LIG2 ... LIGN [0]' Glyphs LIG1, LIG2, ..., LIGN are ligatures; possible ligatures are `ff', `fi', `fl', `ffi' and `ffl'. For backwards compatibility, the list of ligatures may be terminated with a 0. The list of ligatures may not extend over more than one line. `special' The font is "special"; this means that when a glyph is requested that is not present in the current font, it is searched for in any special fonts that are mounted. Other commands are ignored by `gtroff' but may be used by postprocessors to store arbitrary information about the font in the font file. The first section can contain comments which start with the `#' character and extend to the end of a line. The second section contains one or two subsections. It must contain a `charset' subsection and it may also contain a `kernpairs' subsection. These subsections can appear in any order. Each subsection starts with a word on a line by itself. The word `charset' starts the character set subsection.(1) (*note Font File Format-Footnote-1::) The `charset' line is followed by a sequence of lines. Each line gives information for one glyph. A line comprises a number of fields separated by blanks or tabs. The format is NAME METRICS TYPE CODE [ENTITY-NAME] [`--' COMMENT] NAME identifies the glyph name(2) (*note Font File Format-Footnote-2::): If NAME is a single character C then it corresponds to the `gtroff' input character C; if it is of the form `\C' where C is a single character, then it corresponds to the special character `\[C]'; otherwise it corresponds to the special character `\[NAME]'. If it is exactly two characters XX it can be entered as `\(XX'. Note that single-letter special characters can't be accessed as `\C'; the only exception is `\-' which is identical to `\[-]'. `gtroff' supports 8-bit input characters; however some utilities have difficulties with eight-bit characters. For this reason, there is a convention that the entity name `charN' is equivalent to the single input character whose code is N. For example, `char163' would be equivalent to the character with code 163 which is the pounds sterling sign in the ISO Latin-1 character set. You shouldn't use `charN' entities in font description files since they are related to input, not output. Otherwise, you get hard-coded connections between input and output encoding which prevents use of different (input) character sets. The name `---' is special and indicates that the glyph is unnamed; such glyphs can only be used by means of the `\N' escape sequence in `gtroff'. The TYPE field gives the glyph type: `1' the glyph has a descender, for example, `p'; `2' the glyph has an ascender, for example, `b'; `3' the glyph has both an ascender and a descender, for example, `('. The CODE field gives the code which the postprocessor uses to print the glyph. The glyph can also be input to `gtroff' using this code by means of the `\N' escape sequence. CODE can be any integer. If it starts with `0' it is interpreted as octal; if it starts with `0x' or `0X' it is interpreted as hexadecimal. Note, however, that the `\N' escape sequence only accepts a decimal integer. The ENTITY-NAME field gives an ASCII string identifying the glyph which the postprocessor uses to print the `gtroff' glyph NAME. This field is optional and has been introduced so that the HTML device driver can encode its character set. For example, the glyph `\[Po]' is represented as `£' in HTML 4.0. Anything on the line after the ENTITY-NAME field resp. after `--' will be ignored. The METRICS field has the form: WIDTH[`,'HEIGHT[`,'DEPTH[`,'ITALIC-CORRECTION [`,'LEFT-ITALIC-CORRECTION[`,'SUBSCRIPT-CORRECTION]]]]] There must not be any spaces between these subfields (it has been split here into two lines for better legibility only). Missing subfields are assumed to be 0. The subfields are all decimal integers. Since there is no associated binary format, these values are not required to fit into a variable of type `char' as they are in `ditroff'. The WIDTH subfield gives the width of the glyph. The HEIGHT subfield gives the height of the glyph (upwards is positive); if a glyph does not extend above the baseline, it should be given a zero height, rather than a negative height. The DEPTH subfield gives the depth of the glyph, that is, the distance from the baseline to the lowest point below the baseline to which the glyph extends (downwards is positive); if a glyph does not extend below the baseline, it should be given a zero depth, rather than a negative depth. The ITALIC-CORRECTION subfield gives the amount of space that should be added after the glyph when it is immediately to be followed by a glyph from a roman font. The LEFT-ITALIC-CORRECTION subfield gives the amount of space that should be added before the glyph when it is immediately to be preceded by a glyph from a roman font. The SUBSCRIPT-CORRECTION gives the amount of space that should be added after a glyph before adding a subscript. This should be less than the italic correction. A line in the `charset' section can also have the format NAME " This indicates that NAME is just another name for the glyph mentioned in the preceding line. The word `kernpairs' starts the kernpairs section. This contains a sequence of lines of the form: C1 C2 N This means that when glyph C1 appears next to glyph C2 the space between them should be increased by N. Most entries in the kernpairs section have a negative value for N.  File: groff, Node: Font File Format-Footnotes, Up: Font File Format (1) This keyword is misnamed since it starts a list of ordered glyphs, not characters. (2) The distinction between input, characters, and output, glyphs, is not clearly separated in the terminology of `groff'; for example, the `char' request should be called `glyph' since it defines an output entity.  File: groff, Node: Installation, Next: Copying This Manual, Prev: File formats, Up: Top Installation ************  File: groff, Node: Copying This Manual, Next: Request Index, Prev: Installation, Up: Top Copying This Manual ******************* * Menu: * GNU Free Documentation License:: License for copying this manual.