Manual Pages for UNIX Darwin command on man groff

Manual Pages for UNIX Darwin command on man groff_out

GROFFOUT(5) GROFFOUT(5)

NAME

groffout - groff intermediate output format

DESCRIPTION

This manual page describes the intermediate output format of the GNU rrooffff(7) text processing system. This output is produced by a run of the GNU ttrrooffff(1) program before it is fed into a device postprocessor program. As the GNU roff processor ggrrooffff(1) is a wrapper program around troff that automatically calls a postprocessor, this output does not show up

normally. This is why it is called intermediate within the groff sys-

tem. The ggrrooffff program provides the option -ZZ to inhibit postprocess-

ing, such that the produced intermediate output is sent to standard output just like calling ttrrooffff 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 post-

processors. This parser is smarter on whitespace and implements obso-

lete elements for compatibility, otherwise both formats are the same.

The pre-groff roff versions are denoted as classical troff.

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 com-

pletely different from the ggrrooffff(7) language. While the groff language

is a high-level programming language for text processing, the interme-

diate 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 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. LLAANNGGUUAAGGEE CCOONNCCEEPPTTSS

During the run of ttrrooffff, the roff input is cracked down to the informa-

tion 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 doc-

ument, the term "command" always refers to the intermediate output lan-

guage, never to the roff language used for document formatting. There are commands for positioning and text writing, for drawing, and for device controlling. SSeeppaarraattiioonn Classical troff output had strange requirements on whitespace. The groff 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 ssyynnttaacc-

ttiiccaall ssppaaccee. 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 ssyynnttaaccttiiccaall lliinnee bbrreeaakk is defined to consist of optional syntactical

space that is optionally followed by a comment, and a newline charac-

ter.

The normal commands, those for positioning and text, consist of a sin-

gle letter taking a fixed number of arguments. For historical reasons,

the parser allows to stack such commands on the same line, but fortu-

nately, in groff intermediate output, every command with at least one

argument is followed by a line break, thus providing excellent read-

ability.

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 DD and xx commands were designed to request a syntactical line break after their last argument. Only one command, `xx XX' 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, i.e. lines containing only space and/or a comment, can occur everywhere. They are just ignored. AArrgguummeenntt UUnniittss

Some commands take integer arguments that are assumed to represent val-

ues in a measurement unit, but the letter for the corresponding scale indicator is not written with the output command arguments; see ggrrooffff(7) and the groff info file for more on this topic. Most commands assume the scale indicator uu, the basic unit of the device, some use zz, 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 ggrrooffffffoonntt(5). 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 com-

mand. DDooccuummeenntt PPaarrttss

A correct intermediate output document consists of two parts, the pro-

logue and the body. The task of the prologue is to set the general device parameters using three exactly specified commands. The groff prologue is guaranteed to consist of the following three lines (in that order): xx TT device xx rreess n h v xx iinniitt

with the arguments set as outlined in the section DDeevviiccee CCoonnttrrooll CCoomm-

mmaannddss. But 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. Syntac-

tically, it is a sequence of any commands different from the ones used in the prologue. Processing is terminated as soon as the first xx ssttoopp command is encountered; the last line of any groff intermediate output always contains such a command. Semantically, the body is page oriented. A new page is started by a pp command. Positioning, writing, and drawing commands are always done

within the current page, so they cannot occur before the first pp com-

mand. Absolute positioning (by the HH and VV commands) is done relative

to the current page, all other positioning is done relative to the cur-

rent location within this page. CCOOMMMMAANNDD RREEFFEERREENNCCEE This section describes all intermediate output commands, the classical commands as well as the groff extensions. CCoommmmeenntt CCoommmmaanndd

##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. SSiimmppllee CCoommmmaannddss 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 inte-

ger arguments would clash or if the preceding argument ends with a string argument. CC xxx

Print a special groff character named xxx. The trailing syntac-

tical space or line break is necessary to allow character names of arbitrary length. The character is printed at the current print position; the character's size is read from the font file. The print position is not changed. cc c Print character c at the current print position; the character's size is read from the font file. The print position is not changed.

ff n Set font to font number n (a non-negative integer).

HH n Move right to the absolute vertical position n (a non-negative

integer in basic units uu) relative to left edge of current page.

hh n Move n (a non-negative integer) basic units uu horizontally to

the right. [54] allows negative values for n also, but groff doesn't use this. mm colorscheme [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 DDFF. 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 gener-

ated by the groff escape sequence \\mm. No position changing. These commands are a groff extension. mmcc cyan magenta yellow Set color using the CMY color scheme, having the 3 color components cyan, magenta, and yellow. mmdd Set color to the default color value (black in most cases). No component arguments. mmgg gray Set color to the shade of gray given by the argument, an integer between 0 (black) and 65536 (white). mmkk cyan magenta yellow black Set color using the CMYK color scheme, having the 4 color components cyan, magenta, yellow, and black. mmrr red green blue Set color using the RGB color scheme, having the 3 color components red, green, and blue.

NN n Print character with index n (an integer, normally non-negative)

of the current font. The print position is not changed. If

-TT hhttmmll is used, negative values are emitted also to indicate an

unbreakable space with given width. For example, NN -119933 repre-

sents an unbreakable space which has a width of 193u. This com-

mand is a groff extension. nn 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 after 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. pp 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 pp command must be issued before any of these commands. ss n Set point size to n scaled points (this is unit zz in GNU ttrrooffff). Classical troff used the unit points (pp) instead; see section CCOOMMPPAATTIIBBIILLIITTYY. tt xxx tt xxx dummyarg Print a word, i.e. a sequence of characters xxx 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 character should be printed at the current position, the current horizontal position should then be increased by the width of the first character, and so on for each character. The widths of the characters 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 CC com-

mand for named characters). This command is a groff extension;

it is only used for devices whose DESC file contains the ttccoomm-

mmaanndd keyword; see ggrrooffffffoonntt(5). uu n xxx

Print word with track kerning. This is the same as the tt com-

mand except that after printing each character, the current hor-

izontal position is increased by the sum of the width of that character and n (an integer in basic units uu). This command is a groff extension; it is only used for devices whose DESC file contains the ttccoommmmaanndd keyword; see ggrrooffffffoonntt(5).

VV n Move down to the absolute vertical position n (a non-negative

integer in basic units uu) relative to upper edge of current page.

vv n Move n basic units uu down (n is a non-negative integer). [54]

allows negative values for n also, but groff doesn't use this. ww Informs about a paddable whitespace to increase readability.

The spacing itself must be performed explicitly by a move com-

mand. GGrraapphhiiccss CCoommmmaannddss Each graphics or drawing command in the intermediate output starts with

the letter DD followed by one or two characters that specify a subcom-

mand; this is followed by a fixed or variable number of integer argu-

ments that are separated by a single space character. A DD command may

not be followed by another command on the same line (apart from a com-

ment), so each DD command is terminated by a syntactical line break.

troff output follows the classical spacing rules (no space between com-

mand and subcommand, all arguments are preceded by a single space char-

acter), but the parser allows optional space between the command let-

ters 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 uu. The arguments called , , ..., h1, h2, ..., hn stand for hor-

izontal distances where positive means right, negative left. The argu-

ments called , , ..., v1, v2, ..., vn stand for vertical distances

where positive means down, negative up. All these distances are off-

sets relative to the current location. Unless indicated otherwise, each graphics command directly corresponds to a similar groff \\DD escape sequence; see ggrrooffff(7).

Unknown D commands are assumed to be device-specific. Its arguments

are parsed as strings; the whole information is then sent to the post-

processor. In the following command reference, the syntax element means a syntactical line break as defined in section SSeeppaarraattiioonn. DD~~ 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. DDaa 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. DDCC d DDCC d dummyarg Draw a solid circle using the current fill color with diameter d (integer in basic units uu) 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 to the formatter to generate an even number of arguments). This command is a groff extension. DDcc d Draw circle line with diameter d (integer in basic units uu) with leftmost point at the current position; then move the current position to the rightmost point of the circle. DDEE 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 uu) with the leftmost point at the current position; then move to the rightmost point of the ellipse. This command is a groff extension. DDee h v Draw an outlined ellipse with a horizontal diameter of h and a vertical diameter of v (both integers in basic units uu) with the leftmost point at current position; then move to the rightmost point of the ellipse. DDFF colorscheme [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 mm. 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 gener-

ated by the groff escape sequences \\DD''FF ......'' and \\MM (with no other corresponding graphics commands). No position changing. This command is a groff extension. DDFFcc cyan magenta yellow Set fill color for solid drawing objects using the CMY color scheme, having the 3 color components cyan, magenta, and yellow. DDFFdd Set fill color for solid drawing objects to the default fill color value (black in most cases). No component arguments. DDFFgg 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). DDFFkk 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. DDFFrr red green blue Set fill color for solid drawing objects using the RGB color scheme, having the 3 color components red, green, and blue. DDff 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 DDFFgg. 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 mm. For example, the command sequence mmgg 00 00 6655553366

DDff -11

sets all colors to blue. No position changing. This command is a groff extension. DDll h v Draw line from current position to offset (h, v) (integers in basic units uu); then set current position to the end of the drawn line. DDpp 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 rea-

sons, 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 groff exten-

sion. DDPP h1 v1 h2 v2 ... hn vn The same macro as the corresponding DDpp 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 DDpp. This command is a groff extension. DDtt n Set the current line thickness to n (an integer in basic units uu) 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 DDtt command was specified). For historical reasons, the horizontal position is

changed by adding the argument to the actual horizontal posi-

tion, while the vertical position is not changed. Although this doesn't make sense it is kept for compatibility. This command is a groff extension. DDeevviiccee CCoonnttrrooll CCoommmmaannddss Each device control command starts with the letter xx followed by a

space character (optional or arbitrary space/tab in groff) and a sub-

command letter or word; each argument (if any) must be preceded by a syntactical space. All xx 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 readabil-

ity, it can be written as a word, i.e. an arbitrary sequence of charac-

ters 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 xx ii as xx iinniitt and the resolution command xx rr as xx rreess. But writings like xx iilliikkeeggrrooffff

and xx rrooffffiissggrrooffff resp. are accepted as well to mean the same com-

mands. In the following, the syntax element means a syntactical line break as defined in section SSeeppaarraattiioonn. xxFF name (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. xxff n s (font control command)

Mount font position n (a non-negative integer) with font named s

(a text word), cf. ggrrooffffffoonntt(5). xxHH n (Height control command) Set character height to n (a positive integer in scaled points zz). Classical troff used the unit points (pp) instead; see section CCOOMMPPAATTIIBBIILLIITTYY. xxii (init control command) Initialize device. This is the third command of the prologue. xxpp (pause control command) Parsed but ignored. The classical documentation reads pause device, can be restarted. xxrr n h v (resolution control command) Resolution is n, while h is the minimal horizontal motion, and v

the minimal vertical motion possible with this device; all argu-

ments are positive integers in basic units uu per inch. This is the second command of the prologue. xxSS n (Slant control command) Set slant to n degrees (an integer in basic units uu). xxss (stop control command) Terminates the processing of the current file; issued as the last command of any intermediate troff output. xxtt (trailer control command)

Generate trailer information, if any. In groff, this is actu-

ally just ignored. xxTT xxx (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 -TT option. This is the first

command of the prologue. xxuu n (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 ccuu request in nroff mode and is ignored other-

wise. This command is a groff extension. xxXX anything

(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 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

groff escape sequence \\XX. The line-continuing feature is a

groff extension. OObbssoolleettee CCoommmmaanndd In classical troff output, the writing of a single character was mostly done by a very strange command that combined a horizontal move and the

printing of a character. It didn't have a command code, but is repre-

sented by a 3-character argument consisting of exactly 2 digits and a

character. ddc Move right dd (exactly two decimal digits) basic units uu, then print character 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 variable length a sep-

arating space is obligatory. In classical troff, large clusters of these and other commands were 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 characters can become much larger than two decimal digits. In groff, this is only used for the devices XX7755,

XX7755-1122, XX110000, and XX110000-1122. For other devices, the commands tt and uu

provide a better functionality. PPOOSSTTPPRROOCCEESSSSIINNGG 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 postpro-

cessors an easy task. There is a library function that parses the intermediate output and sends the information obtained 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 refer-

ne n eto FILES. EEXXAAMMPPLLEESS This section presents the intermediate output generated from the same input for three different devices. The input is the sentence hell world fed into groff on the command line.

+o High-resolution device ps

shell> eecchhoo hheellll wwoorrlldd || ggrrooffff -ZZ -TT ppss

xx TT ppss xx rreess 7722000000 11 11 xx iinniitt pp11 xx ffoonntt 55 TTRR ff55 ss1100000000 VV1122000000 HH7722000000 tthheellll wwhh22550000 ttww HH9966662200 ttoorrlldd nn1122000000 00 xx ttrraaiilleerr VV779922000000 xx ssttoopp

This output can be fed into the postprocessor ggrrooppss(1) to get its rep-

resentation as a PostScript file.

+o Low-resolution device latin1

This is similar to the high-resolution device except that the posi-

tioning is done at a minor scale. Some comments (lines starting with

#) were added for clarification; they were not generated by the for-

matter.

shell> eecchhoo hheellll wwoorrlldd || ggrrooffff -ZZ -TT llaattiinn11

# prologue

xx TT llaattiinn11 xx rreess 224400 2244 4400 xx iinniitt

# begin a new page

pp11

# font setup

xx ffoonntt 11 RR ff11 ss1100

# initial positioning on the page

VV4400 HH00

# write text `hell'

tthheellll

# inform about a space, and do it by a horizontal jump

wwhh2244

# write text `world'

ttwwoorrlldd

# announce line break, but do nothing because ...

nn4400 00

# ... the end of the document has been reached

xx ttrraaiilleerr VV22664400 xx ssttoopp

This output can be fed into the postprocessor ggrroottttyy(1) to get a for-

matted text document. +o Classical style output As a computer monitor has a very low resolution compared to modern

printers the intermediate output for the X devices can use the jump-

and-write command with its 2-digit displacements.

shell> eecchhoo hheellll wwoorrlldd || ggrrooffff -ZZ -TT XX110000

xx TT XX110000 xx rreess 110000 11 11 xx iinniitt pp11 xx ffoonntt 55 TTRR ff55 ss1100 VV1166 HH110000

# write text with old-style jump-and-write command

cchh0077ee0077ll0033llww0066ww1111oo0077rr0055ll0033ddhh77 nn1166 00 xx ttrraaiilleerr VV11110000 xx ssttoopp This output can be fed into the postprocessor xxddiittvviieeww(1x) or ggxxddiittvviieeww(1) for displaying in X.

Due to the obsolete jump-and-write command, the text clusters in the

classical output are almost unreadable. CCOOMMPPAATTIIBBIILLIITTYY

The intermediate output language of the classical troff was first docu-

mented in [97]. The groff intermediate output format is compatible with this specification except for the following features. +o The classical quasi device independence is not yet implemented. +o The old hardware was very different from what we use today. So the

groff devices are also fundamentally different from the ones in clas-

sical troff. For example, the classical PostScript 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 imple-

menting some rescaling mechanism similar to the classical quasi device independence, these could be integrated into modern groff.

+o The B-spline command DD~~ is correctly handled by the intermediate out-

put parser, but the drawing routines aren't implemented in some of the postprocessor programs. +o The argument of the commands ss and xx HH has the implicit unit scaled point zz in groff, while classical troff had point (pp). This isn't an incompatibility, but a compatible extension, for both units coincide

for all devices without a sizescale parameter, including all classi-

cal 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 conflicts with classical devices are very unlikely. +o The position changing after the commands DDpp, DDPP, and DDtt is illogical,

but as old versions of groff used this feature it is kept for compat-

ibility reasons. The differences between groff and classical troff are documented in ggrrooffffddiiffff(7). FILES //uussrr//sshhaarree//ggrrooffff//11..1199..11//ffoonntt//ddeevvname//DDEESSCC Device description file for device name. //ssrrcc//lliibbss//lliibbddrriivveerr//iinnppuutt..ccpppp

Defines the parser and postprocessor for the intermediate out-

put. It is located relative to the top directory of the groff source tree, e.g. @GROFFSRCDIR@. This parser is the definitive specification of the groff intermediate output format.