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.TL

Troff User's Manual

.AU

Joseph F. Ossanna

Brian W. Kernighan

.sp

bwk@research.bell-labs.com

.EQ

delim @@

define cw % "\&" font CW %

.EN

.SH

Introduction

.PP

\*(Tr and \*(NR are text processors 

that format text for typesetter- and

typewriter-like terminals, respectively.

They accept lines of text interspersed with lines of

format control information and

format the text into a printable, paginated document

having a user-designed style.

\*(Tr and \*(NR offer

unusual freedom in document styling:

arbitrary style headers and footers;

arbitrary style footnotes;

multiple automatic sequence numbering for paragraphs, sections, etc;

multiple column output;

dynamic font and point-size control;

arbitrary horizontal and vertical local motions at any point;

and

a family of automatic overstriking, bracket construction, and

line-drawing functions.

.

.de TL

.LP

.ce

.ps +2

.ft B

..

.

.PP

.I Troff

produces its output in a device-independent form,

although parameterized for a specific device;

\*(TR output must be processed by a driver for that

device to produce printed output.

.PP

\*(Tr and \*(NR are highly compatible with each other and it is almost always

possible to prepare input acceptable to both.

Conditional input is provided to enable

the user to embed input expressly destined for either program.

\*(Nr can prepare output directly for a variety of terminal types and

is capable of utilizing the full resolution of each terminal.

\*(Nr is the same program as \*(TR; in fact, on Plan 9 

\*(NR is a shell script that calls \*(TR with the

.CW -N

argument.

.SH

Background to the Plan 9 Edition

.PP

The primary change to \*(TR and \*(NR for Plan 9 is

support of the Unicode Standard, which was added during

1992 and 1993.  There are two results.  First, there is much

less need for the myriad of two-character names that are so

much a part of \*(TR lore; in Plan 9, for example, one naturally uses the

Unicode character ½ instead of \*(TR\|'s

.CW \\e(12 .

Second, the output device, though called

.CW utf ,

is almost always a form of PostScript printer;

the panoply of special drivers for different typesetters

has largely disappeared.

Unfortunately, not all PostScript printers can cope

with Unicode characters, so there remains a need for

programs that synthesize PostScript characters from bitmaps;

this is especially true for Asian languages.

.SH

Background to the Second Edition

.PP

\*(Tr

was originally written by the late Joe Ossanna

in about 1973, in assembly language for the

.UC PDP -11,

to drive the Graphic Systems CAT typesetter.

It was rewritten in C around 1975,

and underwent slow but steady evolution until

Ossanna's death late in 1977.

.PP

In 1979, Brian Kernighan

modified

\*(TR

so that it would produce output for a variety of typesetters,

while retaining its input specifications.

Over the decade from 1979 to 1989,

the internals

have been modestly revised,

though much of the code remains as it was when Ossanna wrote it.

.PP

\*(Tr

reads parameter files

each time it is invoked, to

set values for machine resolution,

legal type sizes and fonts, and character names,

character widths

and the like.

\*(Tr

output is

.UC ASCII

characters

in a simple language

that describes where each character is to be placed

and in what size and font.

A post-processor must be written for each device

to convert this typesetter-independent language

into specific instructions for that device.

.PP

The output language contains information that was not readily

identifiable in the older output.

In the newer language, the beginning of each page, line, and word

is marked,

so post-processors can do device-specific optimizations

such as sorting the data vertically or printing it boustrophedonically,

independent of

\*(TR.

.PP

Capabilities for graphics have been added:

\*(TR

recognizes commands for drawing diagonal lines,

circles, ellipses, circular arcs,

and quadratic B-splines.

There are also ways to pass arbitrary information to the output,

unprocessed by

\*(TR.

.PP

A number of limitations have been eased or eliminated.

A document may have an arbitrary number of fonts on any page

(if the output device permits it, of course).

Fonts may be accessed merely by naming them;

``mounting'' is no longer necessary.

There are no limits on the number of characters.

\H'8'Character height\H'10' and \S'-1'sl\S'0'a\S'1'nt\S'0' may be set

independently of width.

.PP

The remainder of this document contains a description of

usage and command-line options;

a summary of requests, escape sequences, and pre-defined number registers;

a reference manual;

tutorial examples;

and a list of commonly-available characters.

.SH

Acknowledgements

.PP

Joe Ossanna's

\*(TR

remains a remarkable accomplishment.

For more than twenty years, it has proven a robust tool,

taking unbelievable abuse from a variety of preprocessors

and being forced into uses that were never conceived of

in the original design,

all with considerable grace under fire.

.PP

Recent versions of \*(TR have profited from

significant code improvements by

Jaap Akkerhuis, Dennis Ritchie, Ken Thompson, and Molly Wagner.

UTF facilities owe much to Jaap Akkerhuis.

Andrew Hume, Doug McIlroy, Peter Nelson and Ravi Sethi made valuable suggestions on the manual.

I fear that the remaining bugs are my fault.

.sp 100

.BP

.TL

Usage

.SP

.PP

\*(Tr or \*(NR is invoked as

.P1

troff  \fIoptions  files\fP

nroff  \fIoptions  files\fP

.P2

where @options@ represents any of a number of option arguments

and @files@ represents the list of files containing the document

to be formatted.

An argument consisting of a single minus

.CW - ' `

represents standard input.

If no filenames are given input is taken from the standard input.

The options, which may appear in any order so long as they appear

before the files, are:

.TS

center;

lfCW lw(4.5i).

-m@name@	T{

Read the macro file

@cw /sys/lib/tmac. name@

before the input @files@.

T}

-T@name@	T{

Specifies

the type of the output device.

Specific devices are site-dependent.

For

\*(TR,

the most useful name is

.CW utf .

For

\*(NR,

useful names include

@cw "37"@ for the (default) Model 37 Teletype,

@cw lp@ for ``dumb'' line printer terminals (no half-line motions,

no reverse motions),

and @cw think@ for the HP ThinkJet printer.

T}

-i	T{

Read standard input after the input files are exhausted.

T}

-o@list@	T{

Print only pages whose page numbers appear in @list@,

which consists of comma-separated numbers and number ranges.

A number range has the form @N-M@

and means pages @N@ through @M@;

a initial @-N@ means

from the beginning to page @N@; and a final @N-@ means

from @N@ to the end.

T}

-n@N@	T{

Number first generated page @N@.

T}

-r@aN@	T{

Set number register @a@ (one-character) to @N@.

T}

-s@N@	T{

Stop every @N@ pages.

\*(Nr will halt prior to every @N@ pages (default @N=1@)

to allow paper loading or

changing, and will resume upon receipt of a newline.

\*(Tr will include a ``pause'' code every @N@ pages;

its meaning, if any, depends on the output device.

T}

-u@N@	T{

Set amount of emboldening for the

.CW bd

request to @N@.

T}

-F@path@	T{

Look in directory @path@ for font information;

the defaults are

.CW /sys/lib/troff/font

and

.CW /sys/lib/troff/term

for \*(TR

and \*(NR respectively.

T}

.sp .5

	T{

                  \*(TR Only

T}

-a	T{

Send a printable approximation

of the results to the standard output.

T}

.sp .5

	T{

                  \*(NR Only

T}

-e	T{

Produce equally-spaced words in adjusted

lines, using full terminal resolution.

T}

-h	T{

Use tabs instead of spaces

to speed up printing.

T}

-q	T{

Invoke the simultaneous input-output mode of the @cw rd@ request.

T}

.TE

.PP

Each option is a separate argument;

for example,

.P1

troff -Tutf -ms -mpictures -o4,6,8-10 \f2file1 file2\fP

.P2

requests formatting of pages 4, 6, and 8 through 10 of a document contained in the files

named \f2file1\fP and \f2file2\fP,

specifies the output in UTF,

and invokes the macro packages

.CW -ms

and

.CW -mpictures .

.PP

Various pre- and post-processors are available for use with \*(NR and \*(TR.

These include the equation preprocessor

.I eqn

(for \*(TR only),

the table-construction preprocessor

.I tbl ,

and

.I pic 

and

.I grap

for various forms of graphics.

.sp 100

.BP

.TL

Request Summary

.PP

In the following table,

the notation @+- N@ in the

.BI "Request Form

column means that the forms @N@, @+N@, or @-N@ are permitted,

to set the parameter to @N@, increment it by @N@, or decrement it by @N@,

respectively.

Plain @N@ means that the value is used to set the parameter.

.BI "Initial Values

separated by 

.CW ;

are for

\*(TR

and

\*(NR

respectively.

In the 

.BI Notes

column,

.TS

center;

c lw(4.5i).

B	T{

Request normally causes a break.

The use of

.CW ' \&

as control character (instead of

.CW . )\&

suppresses the break function.

T}

D	T{

Mode or relevant parameters associated with current diversion level.

T}

E	T{

Relevant parameters are a part of the current environment.

T}

O	T{

Must stay in effect until logical output.

T}

P	T{

Mode must be still or again in effect at the time of physical output.

T}

T	T{

\*(TR only; no effect in \*(NR.

T}

@bold v@, @bold p@, @bold m@, @bold u@	T{

Default scale indicator; if not specified, scale indicators are ignored.

T}

.TE

.sp

.tr &.

.ps 9

.vs 11

.nr z 0 1

.TS

lf2 lf2 lf2 lf2 lf2

lf2 lf2 lf2 lf2 lf2

lfCW l l l l.

Request	Initial	If No

Form	Value	Argument	Notes	Explanation

.sp .5

.T&

lf3 s s s s.

\\n+z.  General Information

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Font and Character Size Control

.sp .5

&ps @+- N@	10 point	previous	E,T	Point size; also @cw "\es" +- N@.

&ss @N@	12/36\fBm\fP	ignored	E,T	Space-character size set to @N/36@ em.

&cs @ F~N~ M@	off	-	P,T	Constant character space (width) mode (font @F@).

&bd @F~N@	off	-	P,T	Embolden font @F@ by @N-1@ units.

&bd S@~F~N@	off	-	P,T	Embolden Special Font when current font is @F@.

&ft@~F@	Roman	previous	E	Change to font @F@; also @cw "\ef" x@, @cw "\ef(" xx@, @cw "\ef" N@.

&fp@~N~F~L@	R,I,B,...,S	ignored	-	Mount font named @F@ on physical position @N <= 1@;

				  long name is @L@ if given.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Page Control

&pl @+- N@	11i	11i	@bold v@	Page length.

&bp @+- N@	@N=1@	-	B,@bold v@	Eject current page; next page number @N@.

&pn @+- N@	@N=1@	ignored	-	Next page number @N@.

&po @+- N@	1i; 0	previous	@bold v@	Page offset.

&ne @N@	-	@N=1 roman v@	D,@bold v@	Need @N@ vertical space.

&mk @R@	none	internal	D	Mark current vertical place in register @R@.

&rt @+- N@	none	internal	D,@bold v@	Return (upward only) to marked vertical place.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Text Filling, Adjusting, and Centering

&br	-	-	B	Break.

&fi	fill	-	B,E	Fill output lines.

&nf	fill	-	B,E	No filling or adjusting of output lines.

&ad @c@	adj, both	adjust	E	Adjust output lines with mode @c@;  @c = cw l , cw r , cw c , cw b , none@

&na	adjust	-	E	No output line adjusting.

&ce @N@	off	@N=1@	B,E	Center next @N@ input text lines.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Vertical Spacing

&vs @N@	12p; 1/6i	previous	E,@bold p@	Vertical baseline spacing (@V@).

&ls @N@	@N=1@	previous	E	Output @N-1@ @bold v@'s after each text output line.

&sp @N@	-	@N=1@v	B,@bold v@	Space vertical distance @N@ in either direction.

&sv @N@	-	@N=1@v	@bold v@	Save vertical distance @N@.

&os	-	-	-	Output saved vertical distance.

&ns	space	-	D	Turn no-space mode on.

&rs	-	-	D	Restore spacing; turn no-space mode off.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Line Length and Indenting

&ll @+- N@	6.5i	previous	E,@bold m@	Line length.

&in @+- N@	@N=0@	previous	B,E,@bold m@	Indent.

&ti @+- N@	-	ignored	B,E,@bold m@	Temporary indent.

.sp .5

.ne 2.1

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Macros, Strings, Diversion, and Position Traps

&de @xx~yy@	-	@.yy= cw ".."@	-	Define or redefine macro @xx@; end at call of @yy@.

&am @xx~yy@	-	@.yy= cw ".."@	-	Append to a macro.

&ds @xx~string@	-	ignored	-	Define a string @xx@ containing @string@.

&as @xx~string@	-	ignored	-	Append @string@ to string @xx@.

&rm @xx@	-	ignored	-	Remove request, macro, or string.

&rn @xx~yy@	-	ignored	-	Rename request, macro, or string @xx@ to @yy@.

&di @xx@	-	end	D	Divert output to macro @xx@.

&da @xx@	-	end	D	Divert and append to @xx@.

&wh @N~xx@	-	-	@bold v@	Set location trap; negative is w.r.t. page bottom.

&ch @xx~N@	-	-	@bold v@	Change trap location.

&dt @N~xx@	-	off	D,@bold v@	Set a diversion trap.

&it @N~xx@	-	off	E	Set an input-line count trap.

&em @xx@	none	none	-	End macro is @xx@.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Number Registers

&nr @R~+- N~M@		-	@bold u@	Define and set number register @R@;

				  auto-increment by @M@.

&af @R~c@	arabic	-	-	Assign format to register @R@ (@c= cw "1" , cw i , cw I , cw a , cw A@).

&rr @R@	-	-	-	Remove register @R@.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Tabs, Leaders, and Fields

&ta@~Nt~. . .@	0.5i; 0.8n	none	E,@bold m@	Tab settings; left-adjusting, unless

				  @t= cw R@ (right), @cw C@ (centered).

&tc@~c@	none	none	E	Tab repetition character.

&lc@~c@	@cw "."@	none	E	Leader repetition character.

&fc@~a~b@	off	off	-	Set field delimiter @a@ and pad character @b@.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Input and Output Conventions and Character Translations

&ec@~c@	\e	\e	-	Set escape character.

&eo	on	-	-	Turn off escape character mechanism.

&lg@~N@	on; -	on	T	Ligature mode on if @N>0@.

&ul@~N@	off	@N=1@	E	Underline (italicize in \*(TR\^) @N@ input lines.

&cu@~N@	off	@N=1@	E	Continuous underline in \*(NR; in \*(TR, like @cw ul@.

&uf@~F@	Italic	Italic	-	Underline font set to @F@ (to be switched to by @cw ul@).

&cc@~c@	@cw .@	@cw .@	E	Set control character to @c@.

&c2@~c@	@cw "'"@	@cw "'"@	E	Set no-break control character to @c@.

&tr@~abcd....@	none	-	O	Translate @a@ to @b@, etc., on output.

.sp .5

.T&

lf3 s s s s.

\\n+z.  Local Horizontal and Vertical Motions, and the Width Function

.sp .5

.T&

lf3 s s s s.

\\n+z.  Overstrike, Bracket, Line-drawing, Graphics, and Zero-width Functions

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Hyphenation.

&nh	hyphenate	-	E	No hyphenation.

&hy@~N@	hyphenate	hyphenate	E	Hyphenate; @N =@ mode.

&hc@~c@	@cw "\e%"@	@cw "\e%"@	E	Hyphenation indicator character @c@.

&hw@~word~. . .@		ignored	-	Add words to hyphenation dictionary.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Three-Part Titles.

&tl@~'l'c'r'@		-	-	Three-part title; delimiter may be any character.

&pc@~c@	@cw %@	off	-	Page number character.

&lt@~+- N@	6.5i	previous	E,@bold m@	Length of title.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Output Line Numbering.

&nm@~+- N^M^S^I@		off	E	Number mode on or off, set parameters.

&nn@~N@	-	@N=1@	E	Do not number next @N@ lines.

.sp .5

.ne 2

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Conditional Acceptance of Input

&if@~c~any@		-	-	If condition @c@ true, accept @any@ as input;

				  for multi-line, use @cw "\e{" any cw "\e}"@.

&if !@c~any@		-	-	If condition @c@ false, accept @any@.

&if@~N~any@		-	@bold u@	If expression @N > 0@, accept @any@.

&if !@N~any@		-	@bold u@	If expression @N <= 0@ [sic], accept @any@.

&if@~ 's1 's2 '~any@		-	-	If string @s1@ identical to @s2@, accept @any@.

&if !@ 's1 's2 '~any@		-	-	If string @s1@ not identical to @s2@, accept @any@.

&ie@~c~any@		-	@bold u@	If portion of if-else; all above forms (like @cw "if"@).

&el@~any@		-	-	Else portion of if-else.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Environment Switching

&ev@~N@	@N=0@	previous	-	Environment switch (push down).

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Insertions from the Standard Input

&rd@~prompt@	-	@prompt@=\s-1BEL\s+1	-	Read insertion.

&ex	-	-	-	Exit.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Input/Output File Switching

&so@~filename@		-	-	Switch source file (push down).

&nx@~filename@		end-of-file	-	Next file.

&sy@~string@		-	-	Execute program @string@.  Output not interpolated.

&pi@~string@		-	-	Pipe output to program @string@.

&cf@~filename@		-	-	Copy file contents to \*(TR output.

.sp .5

.T&

lf3 s s s s

lfCW l l l l.

\\n+z.  Miscellaneous

&mc@~c~N@	-	off	E,@bold m@	Set margin character @c@ and separation @N@.

&tm@~string@	-	newline	-	Print @string@ on terminal (standard error).

&ab@~string@	-	newline	-	Print @string@ on standard error, exit program.

&ig@~yy@	-	@.yy= cw ".."@	-	Ignore input until call of @yy@.

&lf@~N ~f@		-	-	Set input line number to @N@ and filename to @f@.

&pm@~t@	-	all	-	Print macro names, sizes; if @t@ present, print total.

&fl	-	-	B	Flush output buffer.

.sp .5

.T&

lf3 s s s s.

\\n+z.  Output and Error Messages

.sp .5

\\n+z.  Output Language

.sp .5

\\n+z.  Device and Font Description Files

.TE

.br

.nr zz 9

.de cl

.ie \\n+(cl<\n(zz \{\

.	po +\\n(.lu/\n(zzu

.	rt\}

.el \{.po 1i\}

..

.nr cl 0 1

.di zz

.ta .45iR

... was .35

.nf

.ps 9

.vs 10.5

\f(CWab\fP	20

\f(CWad\fP	4

\f(CWaf\fP	8

\f(CWam\fP	7

\f(CWas\fP	7

\f(CWbd\fP	2

\f(CWbp\fP	3

\f(CWbr\fP	4

\f(CWc2\fP	10

\f(CWcc\fP	10

\f(CWce\fP	4

\f(CWcf\fP	19

\f(CWch\fP	7

\f(CWcs\fP	2

\f(CWcu\fP	10

\f(CWda\fP	7

\f(CWde\fP	7

\f(CWdi\fP	7

\f(CWds\fP	7

\f(CWdt\fP	7

\f(CWec\fP	10

\f(CWel\fP	16

\f(CWem\fP	7

\f(CWeo\fP	10

\f(CWev\fP	17

\f(CWex\fP	18

\f(CWfc\fP	9

\f(CWfi\fP	4

\f(CWfl\fP	20

\f(CWfp\fP	2

\f(CWft\fP	2

\f(CWhc\fP	13

\f(CWhw\fP	13

\f(CWhy\fP	13

\f(CWie\fP	16

\f(CWif\fP	16

\f(CWig\fP	20

\f(CWin\fP	6

\f(CWit\fP	7

\f(CWlc\fP	9

\f(CWlg\fP	10

\f(CWlf\fP	20

\f(CWll\fP	6

\f(CWls\fP	5

\f(CWlt\fP	14

\f(CWmc\fP	20

\f(CWmk\fP	3

\f(CWna\fP	4

\f(CWne\fP	3

\f(CWnf\fP	4

\f(CWnh\fP	13

\f(CWnm\fP	15

\f(CWnn\fP	15

\f(CWnr\fP	8

\f(CWns\fP	5

\f(CWnx\fP	19

\f(CWos\fP	5

\f(CWpc\fP	14

\f(CWpi\fP	19

\f(CWpl\fP	3

\f(CWpm\fP	20

\f(CWpn\fP	3

\f(CWpo\fP	3

\f(CWps\fP	2

\f(CWrd\fP	18

\f(CWrm\fP	7

\f(CWrn\fP	7

\f(CWrr\fP	8

\f(CWrs\fP	5

\f(CWrt\fP	3

\f(CWso\fP	19

\f(CWsp\fP	5

\f(CWss\fP	2

\f(CWsv\fP	5

\f(CWsy\fP	19

\f(CWta\fP	9

\f(CWtc\fP	9

\f(CWti\fP	6

\f(CWtl\fP	14

\f(CWtm\fP	20

\f(CWtr\fP	10

\f(CWuf\fP	10

\f(CWul\fP	10

\f(CWvs\fP	5

\f(CWwh\fP	7

.di

.nr aa \n(dn/\n(zz

.ne \\n(aau+10p

.sp

.SP 2

.TL

Alphabetical Request and Section Number Cross Reference

.SP .5

.LP

.sp .5

.nf

.wh \n(nlu+\n(aau cl

.nr qq \n(nlu+\n(aau

.ps

.vs

.mk

.zz

.rt

.sp \n(.tu

.ch cl 12i

.sp 100

.BP

.TL

Escape Sequences for Characters, Indicators, and Functions

.SP .5

.LP

.ps -1

.vs -1

.TS

center;

c2 l

c2 l2 l

n2 l2fCW l.

.ft 4

Section	Escape

Reference	Sequence	Meaning

.ft

.sp .5

10.1	\e\e	\&\f(CW\e\fP prevents or delays the interpretation of \&\f(CW\e\fP

10.1	\ee	Printable version of the current escape character.

2.1	\e'	\' (acute accent); equivalent to \&\f(CW\e(aa\fP

2.1	\e`	\` (grave accent); equivalent to \&\f(CW\e(ga\fP

2.1	\e\-	\- Minus sign in the current font

7.	\e\^.	Period (dot) (see \&\f(CWde\fP)

11.1	\e\f2space\fP	Unpaddable space-size space character

11.1	\e0	Digit width space

11.1	\e|	1/6 em narrow space character (zero width in \*(NR\^)

11.1	\e^	1/12 em half-narrow space character (zero width in \*(NR\^)

.tr &&

4.1	\e&	Non-printing, zero width character

.tr &.

10.6	\e!	Transparent line indicator

10.8	\e"	Beginning of comment; continues to end of line

13.	\e%	Default optional hyphenation character

2.1	\e(@xx@	Character named @xx@

7.1	\e*@x,~@\e*(@xx@	Interpolate string @x@ or @xx@

7.3	\e$@N@	Interpolate argument @1 <= N <= 9@

9.1	\ea	Non-interpreted leader character

12.3	\eb'@abc...@'	Bracket building function

4.2	\ec	Connect to next input text

2.1	\eC'@xyz@'	Character named @xyz@

11.1	\ed	Downward 1/2 em vertical motion (1/2 line in \*(NR\^)

12.5	\eD'@c...@'	Draw graphics function @c@ with parameters @. . .@; @c= cw l , cw c , cw e , cw a , cw "~"@

2.2	\ef@x,~@\ef(@xx,~@\ef@N@	Change to font named @x@ or @xx@, or position @N@

8.	\eg@x,~@\eg(@xx@	Format of number register @x@ or @xx@

11.1	\eh'@N@'	Local horizontal motion; move right @N@ (negative left)

2.3	\eH'@N@'	Height of current font is @N@

11.3	\ek@x@	Mark horizontal input place in register @x@

12.4	\el'@Nc@'	Horizontal line drawing function (optionally with @c@ )

12.4	\eL'@Nc@'	Vertical line drawing function (optionally with @c@ )

8.	\en@x,~@\en(@xx@	Contents of number register @x@ or @xx@

2.1	\eN'@N@'	Character number @N@ on current font

12.1	\eo'@abc...@'	Overstrike characters @a,~ b,~ c@, ...

4.1	\ep	Break and spread output line

11.1	\er	Reverse 1 em vertical motion (reverse line in \*(NR\^)

2.3	\es@N,~@\es@+- N@	Point-size change function; also @cw "\es(" nn@, @cw "\es" +- cw "(" nn@

2.2	\eS'@N@'	Slant output @N@ degrees

9.1	\et	Non-interpreted horizontal tab

11.1	\eu	Reverse (up) 1/2 em vertical motion (1/2 line in \*(NR\^)

11.1	\ev'@N@'	Local vertical motion; move down N (negative up)

11.2	\ew'@string@'	Width of @string@

5.2	\ex'@N@'	Extra line-space function (negative before, positive after)

10.7	\eX'@string@'	Output @string@ as device control function

12.2	\ez@c@	Print @c@ with zero width (without spacing)

16.	\e{	Begin conditional input

16.	\e}	End conditional input

10.8	\e@newline@	Concealed (ignored) newline

-	\e@Z@	@Z@, any character not listed above

.TE

.ps +1

.vs +1

.LP

The escape sequences

.CW \e\e ,

.CW \e\^. ,

.CW \e" ,

.CW \e$ ,

.CW \e* ,

.CW \ea ,

.CW \en ,

.CW \et ,

.CW \eg ,

and

.CW \e@newline@

are interpreted in copy mode (§7.2).

.SP .5i

\0

.sp 100

.BP

.TL

Predefined Number Registers

.LP

.ps -1

.vs -1

.TS

c2l

c2 l2 l

n2 l2fCW l.

.ft 4

Section	Register

Reference	Name	Description

.ft

.sp .5

3.	%	Current page number.

11.2	ct	Character type (set by \&\f(CW\ew\fP function).

7.4	dl	Width (maximum) of last completed diversion.

7.4	dn	Height (vertical size) of last completed diversion.

-	dw	Current day of the week (1-7).

-	dy	Current day of the month (1-31).

15.	ln	Output line number.

-	mo	Current month (1-12).

4.1	nl	Vertical position of last printed text baseline.

11.2	sb	Depth of string below baseline (generated by \&\f(CW\ew\fP function).

11.2	st	Height of string above baseline (generated by \&\f(CW\ew\fP function).

-	yr	Last two digits of current year.

.TE

.ps +1

.vs +1

.TL

Predefined Read-Only Number Registers

.LP

.ps -1

.vs -1

.TS

c2 l

c2 l2 l

n2 l2fCW l.

.ft 4

Section	Register

Reference	Name	Description

.ft

.sp .5

19.	$$	Process id of \*(TR or \*(NR.

7.3	&$	Number of arguments available at the current macro level.

5.2	&a	Post-line extra line-space most recently used in @cw "\ex'" N cw "'" @.

-	&A	Set to 1 in \*(TR, if @cw -a@ option used; always 1 in \*(NR.

2.3	&b	Emboldening level.

20.	&c	Number of lines read from current input file.

7.4	&d	Current vertical place in current diversion; equal to @cw nl@, if no diversion.

2.2	&f	Current font number.

20.	&F	Current input file name [sic].

4.	&h	Text baseline high-water mark on current page or diversion.

11.1	&H	Available horizontal resolution in basic units.

6.	&i	Current indent.

4.2	&j	Current @cw ad@ mode.

4.1	&k	Current output horizontal position.

6.	&l	Current line length.

5.1	&L	Current @cw ls@ value.

4.	&n	Length of text portion on previous output line.

3.	&o	Current page offset.

3.	&p	Current page length.

7.5	.R	Number of unused number registers.

-	&T	Set to 1 in \*(NR, if \&\f(CW-T\fP option used; always 0 in \*(TR.

2.3	&s	Current point size.

7.5	&t	Distance to the next trap.

4.1	&u	Equal to 1 in fill mode and 0 in nofill mode.

5.1	&v	Current vertical line spacing.

11.1	&V	Available vertical resolution in basic units.

11.2	&w	Width of previous character.

-	&x	Reserved version-dependent register.

-	&y	Reserved version-dependent register.

7.4	&z	Name [sic] of current diversion.

.TE

.ps +1

.vs +1

.sp 100

.BP

.TL

Reference Manual

.NH

General Explanation

.sc "Form of input.

Input consists of \fItext lines\fR, which are destined to be printed,

interspersed with \fIcontrol lines\fR,

which set parameters or otherwise control subsequent processing.

Control lines begin with a \fIcontrol character\fR\(em\

normally \&\f(CW.\fR (period) or \&\f(CW'\fR (single quote)\(em\

followed by a one or two character name that specifies

a basic \fIrequest\fR or the substitution of

a user-defined \fImacro\fR in place of the control line.

The control character \&\f(CW'\fR suppresses the \fIbreak\fR function\(em\

the forced output of a partially filled line\(em\

caused by certain requests.

The control character may be separated from the request/macro name by

white space (spaces and/or tabs) for aesthetic reasons.

Names should be followed by either

space or newline.

Control lines with unrecognized names are ignored.

.PP

Various special functions may be introduced anywhere in the input by

means of an \fIescape\fR character, normally \&\f(CW\e\fR.

For example, the function

.CW \en@R@

causes the interpolation of the contents of the

\fInumber register R\fR

in place of the function;

here @R@ is either a single character name

as in \&\f(CW\en\fIx\fR,

or a two-character name introduced by

a left-parenthesis, as in \&\f(CW\en(\fIxx\fR.

.sc "Formatter and device resolution.

\*(Tr internally stores and processes dimensions in units that correspond to

the particular device for which output is being prepared;

values from 300 to 1200/inch are typical.

See §23.

\*(Nr internally uses 240 units/inch,

corresponding to the least common multiple of the

horizontal and vertical resolutions of various

typewriter-like output devices.

\*(Tr rounds horizontal/vertical numerical parameter input to the actual

horizontal/vertical resolution of the output device indicated by the \&\f(CW-T\fR option

(default

.CW post ).

\*(Nr similarly rounds numerical input to the actual resolution

of its output device

(default Model 37 Teletype).

.sc "Numerical parameter input.

Both \*(NR and \*(TR

accept numerical input with the appended scale

indicators

shown in the following table,

where

\fIS\fR is the current type size in points and

\fIV\fR is the current vertical line spacing in

basic units.

.TS

center box;

c|c

c|c

c|l.

Scale

Indicator	Meaning

_

\&\f(CWi\fR	Inch

\&\f(CWc\fR	Centimeter

\&\f(CWP\fR	Pica = 1/6 inch

\&\f(CWm\fR	Em = \fIS\fR points

\&\f(CWn\fR	En = Em/2

\&\f(CWp\fR	Point = 1/72 inch

\&\f(CWu\fR	Basic unit

\&\f(CWv\fR	Vertical line space \fIV\fR

none	Default, see below

.TE

In \*(NR, both the em and the en are taken to be equal to the

nominal character width,

which is output-device dependent;

common values are 1/10 and 1/12 inch.

Actual character widths in \*(NR need not be all the same and constructed characters