Summary of Changes to N/TROFF Since October 1976 Manual


-h (Nroff only) Output tabs used during horizontal spacing to speed output as well as reduce output byte count. Device tab settings assumed to be every 8 nominal character widths. The default settings of input (logical) tabs is also initialized to every 8 nominal character widths.

-z Efficiently suppresses formatted output. Only message output will occur (from "tm"s and diagnostics).

Old Requests

.ad c The adjustment type indicator "c" may now also be a number previously obtained from the ".j" register (see below).

.so name The contents of file "name" will be interpolated at the point the "so" is encountered. Previously, the interpolation was done upon return to the file-reading input level.

New Request

.ab text Prints "text" on the message output and terminates without further processing. If "text" is missing, "User Abort." is printed. Does not cause a break. The output buffer is flushed.

.fz F N forces f_ont "F" to be in siz_e N. N may have the form N, +N, or -N. For example, .fz 3 -2
will cause an implicit \s-2 every time font 3 is entered, and a corresponding \s+2 when it is left. Special font characters occurring during the reign of font F will have the same size modification. If special characters are to be treated differently, .fz S F N
may be used to specify the size treatment of special characters during font F. For example, .fz 3 -3 .fz S 3 -0
will cause automatic reduction of font 3 by 3 points while the special characters would not be affected. Any ``.fp'' request specifying a font on some position must precede ``.fz'' requests relating to that position.

New Predefined Number Registers.

.k Read-only. Contains the horizontal size of the text portion (without indent) of the current partially collected output line, if any, in the current environment.

.j Read-only. A number representing the current adjustment mode and type. Can be saved and later given to the "ad" request to restore a previous mode.

.P Read-only. 1 if the current page is being printed, and zero otherwise.

.L Read-only. Contains the current line-spacing parameter ("ls").

c. General register access to the input line-number in the current input file. Contains the same value as the read-only ".c" register.

NROFF/TROFF User's Manual

Joseph F. Ossanna

Bell Laboratories Murray Hill, New Jersey 07974 Introduction
NROFF and TROFF are text processors under the PDP-11 UNIX Time-Sharing System that format text for typewriter-like terminals and for a Graphic Systems phototypesetter, 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. NROFF and TROFF offer unusual freedom in document styling, including: 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.
NROFF and TROFF are highly compatible with each other and it is almost always possible to prepare input acceptable to both. Conditional input is provided that enables the user to embed input expressly destined for either program. NROFF can prepare output directly for a variety of terminal types and is capable of utilizing the full resolution of each terminal.
The general form of invoking NROFF (or TROFF) at UNIX command level is
nroff options files(or troff options files)
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 (-) is taken to be a file name corresponding to the standard input. If no file names 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:

Option Effect

-olist 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.
-nN Number first generated page N.
-sN Stop every N pages. NROFF will halt prior to every N pages (default N=1) to allow paper loading or changing, and will resume upon receipt of a newline. TROFF will stop the phototypesetter every N pages, produce a trailer to allow changing cassettes, and will resume after the phototypesetter START button is pressed.
-mname Prepends the macro file /usr/lib/ to the input files.
-raN Register a (one-character) is set to N.
-i Read standard input after the input files are exhausted.
-q Invoke the simultaneous input-output mode of the rd request.


-Tname Specifies the name of the output terminal type. Currently defined names are 37 for the (default) Model 37 Teletype®, tn300 for the GE TermiNet 300 (or any terminal without half-line capabilities), 300S for the DASI-300S, 300 for the DASI-300, and 450 for the DASI-450 (Diablo Hyterm).
-e Produce equally-spaced words in adjusted lines, using full terminal resolution.


-t Direct output to the standard output instead of the phototypesetter.
-f Refrain from feeding out paper and stopping phototypesetter at the end of the run.
-w Wait until phototypesetter is available, if currently busy.
-b TROFF will report whether the phototypesetter is busy or available. No text processing is done.
-a Send a printable (ASCII) approximation of the results to the standard output.
-pN Print all characters in point size N while retaining all prescribed spacings and motions, to reduce phototypesetter elasped time.
-g Prepare output for the Murray Hill Computation Center phototypesetter and direct it to the standard output.

Each option is invoked as a separate argument; for example,
nroff -o4,8-10 -T300S -mabc file1 file2
requests formatting of pages 4, 8, 9, and 10 of a document contained in the files named file1 and file2, specifies the output terminal as a DASI-300S, and invokes the macro package abc.
Various pre- and post-processors are available for use with NROFF and TROFF. These include the equation preprocessors NEQN and EQN (for NROFF and TROFF respectively), and the table-construction preprocessor TBL. A reverse-line postprocessor COL is available for multiple-column NROFF output on terminals without reverse-line ability; COL expects the Model 37 Teletype escape sequences that NROFF produces by default. TK is a 37 Teletype simulator postprocessor for printing NROFF output on a Tektronix 4014. TCAT is phototypesetter-simulator postprocessor for TROFF that produces an approximation of phototypesetter output on a Tektronix 4014. For example, in
tbl files | eqn | troff -t options | tcat
the first | indicates the piping of TBL's output to EQN's input; the second the piping of EQN's output to TROFF's input; and the third indicates the piping of TROFF's output to TCAT. GCAT can be used to send TROFF (-g) output to the Murray Hill Computation Center.

The remainder of this manual consists of: a Summary and Index; a Reference Manual keyed to the index; and a set of Tutorial Examples. Another tutorial is [5]. Joseph F. Ossanna
[1] K. Thompson, D. M. Ritchie, UNIX Programmer's Manual, Sixth Edition (May 1975). [2] B. W. Kernighan, L. L. Cherry, Typesetting Mathematics -- User's Guide (Second Edition), Bell Laboratories internal memorandum. [3] M. E. Lesk, Tbl -- A Program to Format Tables, Bell Laboratories internal memorandum. [4] Internal on-line documentation, on UNIX. [5] B. W. Kernighan, A TROFF Tutorial, Bell Laboratories internal memorandum.


Request Initial If No
Form Value* Argument Notes# Explanation
*Values separated by "
;" are for NROFF and TROFF respectively. #Notes are explained at the end of this Summary and Index

1. General Explanation
2. Font and Character Size Control
&ps±N 10point previous E Point size; also \s±N.**
&ss|N 12/36em ignored E Space-character size set to N/36em.**
&csFNM off - P Constant character space (width) mode (font F).**
&bd|F|N off - P Embolden font F by N-1 units.**
&bd|S|F|N off - P Embolden Special Font when current font is F.** **No effect in NROFF.

&ft|F Roman previous E Change to font F|= x, xx, or 1-4. Also \fx,\f(xx,\fN.
&fp|N|F R,I,B,S ignored - Font named F mounted on physical position 1<=N<=4.
3. Page Control
&pl±N 11in 11in v Page length.
&bp|±N N=1 - B***,v Eject current page; next page number N. ***The use of " ' " as control character (instead of ".") suppresses the break function.

&pn|±N N=1 ignored - Next page number N.
&po|±N 0;|26/27in previous v Page offset.
&ne|N - N=1V D,v Need N vertical space (V = vertical spacing).
&mk|R none internal D Mark current vertical place in register R.
&rt|±N none internal D,v Return (upward only) to marked vertical place.
4. 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.
&na adjust - E No output line adjusting.
&ce|N off N=1 B,E Center following N input text lines.
5. Vertical Spacing
&vs|N 1/6in;12pts previous E,p Vertical base line spacing (V).
&ls|N N=1 previous E Output N-1 Vs after each text output line.
&sp|N - N=1V B,v Space vertical distance N in either direction.
&sv|N - N=1V 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.
6. Line Length and Indenting
&ll|±N 6.5in previous E,m Line length.
&in|±N N=0 previous B,E,m Indent.
&ti|±N - ignored B,E,m Temporary indent.
7. Macros, Strings, Diversion, and Position Traps
&de|xx|yy - .yy=.. - Define or redefine macro xx; end at call of yy.
&am|xx|yy - .yy=.. - 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 - - v Set location trap; negative is w.r.t. page bottom.
&ch|xx|N - - v Change trap location.
&dt|N|xx - off D,v Set a diversion trap.
&it|N|xx - off E Set an input-line count trap.
&em|xx none none - End macro is xx.
8. Number Registers
&nr|R|±N|M - u Define and set number register R; auto-increment by M.
&af|R|c arabic - - Assign format to register R (c=1, i, I, a, A).
&rr|R - - - Remove register R.
9. Tabs, Leaders, and Fields
&ta|Nt|... 0.8;|0.5in none E,m Tab settings; left type, unless t=R(right), C(centered).
&tc|c none none E Tab repetition character.
&lc|c . none E Leader repetition character.
&fc|a|b off off - Set field delimiter a and pad character b.
10. Input and Output Conventions and Character Translations
&ec|c \ \ - Set escape character.
&eo on - - Turn off escape character mechanism.
&lg|N -;on on - Ligature mode on if N>0.
&ul|N off N=1 E Underline (italicize in TROFF) N input lines.
&cu|N off N=1 E Continuous underline in NROFF; like ul in TROFF.
&uf|F Italic Italic - Underline font set to F (to be switched to by ul).
&cc|c . . E Set control character to c.
&c2|c ' ' E Set nobreak control character to c.
&tr|abcd.... none - O Translate a to b, etc. on output.
11. Local Horizontal and Vertical Motions, and the Width Function
12. Overstrike, Bracket, Line-drawing, and Zero-width Functions
13. Hyphenation.
&nh hyphenate - E No hyphenation.
&hy|N hyphenate hyphenate E Hyphenate; N = mode.
&hc|c \% \% E Hyphenation indicator character c.
&hw|word1|... ignored - Exception words.
14. Three Part Titles.
&tl|'left'center'right' - - Three part title.
&pc|c % off - Page number character.
&lt|±N 6.5in previous E,m Length of title.
15. 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.
16. Conditional Acceptance of Input
&if|c|anything - - If condition c true, accept anything as input,
for multi-line use \{anything\}.
&if|!c|anything - - If condition c false, accept anything.
&if|N|anything - u If expression N > 0, accept anything.
&if|!N|anything - u If expression N <= 0, accept anything.
&if|'string1'string2'|anything - If string1 identical to string2, accept anything.
&if|!'string1'string2'|anything - If string1 not identical to string2, accept anything.
&ie|c|anything - u If portion of if-else; all above forms (like if).
&el|anything - - Else portion of if-else.
17. Environment Switching.
&ev|N N=0 previous - Environment switched (push down).
18. Insertions from the Standard Input
&rd|prompt - prompt=BEL - Read insertion.
&ex - - - Exit from NROFF/TROFF.
19. Input/Output File Switching
&so|filename - - Switch source file (push down).
&nx|filename end-of-file - Next file.
&pi|program - - Pipe output to program (NROFF only).
20. Miscellaneous
&mc|c|N - off E,m Set margin character c and separation N.
&tm|string - newline - Print string on terminal (UNIX standard message output).
&ig|yy - .yy=.. - Ignore till call of yy.
&pm|t - all - Print macro names and sizes;
if t present, print only total of sizes.
&fl - - B Flush output buffer.
21. Output and Error Messages

B Request normally causes a break.
D Mode or relevant parameters associated with current diversion level.
E Relevant parameters are a part of the current environment.
O Must stay in effect until logical output.
P Mode must be still or again in effect at the time of physical output.
v,p,m,u Default scale indicator; if not specified, scale indicators are ignored.

ad 4
af 8
am 7
as 7
bd 2
bp 3
br 4
c2 10
cc 10
ce 4
ch 7
cs 2
cu 10
da 7
de 7
di 7
ds 7
dt 7
ec 10
el 16
em 7
eo 10
ev 17
ex 18
fc 9
fi 4
fl 20
fp 2
ft 2
hc 13
hw 13
hy 13
ie 16
if 16
ig 20
in 6
it 7
lc 9
lg 10
li 10
ll 6
ls 5
lt 14
mc 20
mk 3
na 4
ne 3
nf 4
nh 13
nm 15
nn 15
nr 8
ns 5
nx 19
os 5
pc 14
pi 19
pl 3
pm 20
pn 3
po 3
ps 2
rd 18
rm 7
rn 7
rr 8
rs 5
rt 3
so 19
sp 5
ss 2
sv 5
ta 9
tc 9
ti 6
tl 14
tm 20
tr 10
uf 10
ul 10
vs 5
wh 7

Alphabetical Request and Section Number Cross Reference

Escape Sequences for Characters, Indicators, and Functions

Section Escape
Reference Sequence Meaning
\\ \ (to prevent or delay the interpretation of \)
10.1 \e Printable version of the current escape character.
2.1 \' ' (acute accent); equivalent to \(aa
2.1 \` ` (grave accent); equivalent to \(ga
2.1 \- - Minus sign in the current font
7 \. Period (dot) (see de)
11.1 \(space) Unpaddable space-size space character
11.1 \0 Digit width space
11.1 \| 1/6em narrow space character (zero width in NROFF)
11.1 \^ 1/12em half-narrow space character (zero width in NROFF)
4.1 \& Non-printing, zero width character
10.6 \! Transparent line indicator
10.7 \" Beginning of comment
7.3 \$N Interpolate argument 1<=N<=9
13 \% Default optional hyphenation character
2.1 \(xx Character named xx
7.1 \*x,|\*(xx Interpolate string x or xx
9.1 \a Non-interpreted leader character
12.3 \b'abc...' Bracket building function
4.2 \c Interrupt text processing
11.1 \d Forward (down) 1/2em vertical motion (1/2 line in NROFF)
2.2 \fx,\f(xx,\fN Change to font named x or xx, or position N
11.1 \h'N|' Local horizontal motion; move right N (negative left)
11.3 \kx Mark horizontal input place in register x
12.4 \l'Nc' Horizontal line drawing function (optionally with c)
12.4 \L'Nc' Vertical line drawing function (optionally with c)
8 \nx,\n(xx Interpolate number register x or xx
12.1 \o'abc...' Overstrike characters a, b, c, ...
4.1 \p Break and spread output line
11.1 \r Reverse 1em vertical motion (reverse line in NROFF)
2.3 \sN,\s±N Point-size change function
9.1 \t Non-interpreted horizontal tab
11.1 \u Reverse (up) 1/2em vertical motion (1/2 line in NROFF)
11.1 \v'N' Local vertical motion; move down N (negative up)
11.2 \w'string' Interpolate width of string
5.2 \x'N' Extra line-space function (negative before, positive after)
12.2 \zc Print c with zero width (without spacing)
16 \{ Begin conditional input
16 \} End conditional input
10.7 \(newline) Concealed (ignored) newline
- \X X, any character not listed above

The escape sequences \\, \., \", \$, \*, \a, \n, \t, and \(newline) are interpreted in copy mode (§7.2).
Predefined General Number Registers

Section Register
Reference Name Description
3 % Current page number.
11.2 ct Character type (set by width 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).
11.3 hp Current horizontal place on input line.
15 ln Output line number.
- mo Current month (1-12).
4.1 nl Vertical position of last printed text base-line.
11.2 sb Depth of string below base line (generated by width function).
11.2 st Height of string above base line (generated by width function).
- yr Last two digits of current year.

Predefined Read-Only Number Registers

c2l c2l2l n2l2l. Section Register Reference Name Description
7.3 &$ Number of arguments available at the current macro level. - &A Set to 1 in TROFF, if -a option used; always 1 in NROFF. 11.1 &H Available horizontal resolution in basic units. - &T Set to 1 in NROFF, if -T option used; always 0 in TROFF. 11.1 &V Available vertical resolution in basic units. 5.2 &a Post-line extra line-space most recently utilized using \x'N'. - &c Number of lines read from current input file. 7.4 &d Current vertical place in current diversion; equal to nl, if no diversion. 2.2 &f Current font as physical quadrant (1-4). 4 &h Text base-line high-water mark on current page or diversion. 6 &i Current indent. 6 &l Current line length. 4 &n Length of text portion on previous output line. 3 &o Current page offset. 3 &p Current page length. 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. 11.2 &w Width of previous character. - &x Reserved version-dependent register. - &y Reserved version-dependent register. 7.4 &z Name of current diversion.


22. General Explanation
22.1.Form of input. Input consists of text lines, which are destined to be printed, interspersed with control lines, which set parameters or otherwise control subsequent processing. Control lines begin with a control character--normally . (period) or ' (acute accent)--followed by a one or two character name that specifies a basic request or the substitution of a user-defined macro in place of the control line. The control character ' suppresses the break function--the forced output of a partially filled line--caused by certain requests. The control character may be separated from the request/macro name by white space (spaces and/or tabs) for esthetic reasons. Names must be followed by either space or newline. Control lines with unrecognized names are ignored.
Various special functions may be introduced anywhere in the input by means of an escape character, normally \. For example, the function \nR causes the interpolation of the contents of the number register R in place of the function; here R is either a single character name as in \nx, or left-parenthesis-introduced, two-character name as in \n(xx.
22.2.Formatter and device resolution. TROFF internally uses 432 units/inch, corresponding to the Graphic Systems phototypesetter which has a horizontal resolution of 1/432 inch and a vertical resolution of 1/144 inch. NROFF internally uses 240 units/inch, corresponding to the least common multiple of the horizontal and vertical resolutions of various typewriter-like output devices. TROFF rounds horizontal/vertical numerical parameter input to the actual horizontal/vertical resolution of the Graphic Systems typesetter. NROFF similarly rounds numerical input to the actual resolution of the output device indicated by the -T option (default Model 37 Teletype).
22.3.Numerical parameter input. Both NROFF and TROFF accept numerical input with the appended scale indicators shown in the following table, where S is the current type size in points, V is the current vertical line spacing in basic units, and C is a nominal character width in basic units.

center box; c|c|ls c|c|ll c|l|l|l. Scale Number of basic units Indicator Meaning TROFF NROFF _ i Inch 432 240 c Centimeter 432×50/127 240×50/127 P Pica = 1/6 inch 72 240/6 m Em = S points 6×S C n En = Em/2 3×S C, same as Em p Point = 1/72 inch 6 240/72 u Basic unit 1 1 v Vertical line space V V none Default, see below

In NROFF, both the em and the en are taken to be equal to the C, which is output-device dependent; common values are 1/10 and 1/12 inch. Actual character widths in NROFF need not be all the same and constructed characters such as -> (->) are often extra wide. The default scaling is ems for the horizontally-oriented requests and functions ll, in, ti, ta, lt, po, mc, \h, and \l; Vs for the vertically-oriented requests and functions pl, wh, ch, dt, sp, sv, ne, rt, \v, \x, and \L; p for the vs request; and u for the requests nr, if, and ie. All other requests ignore any scale indicators. When a number register containing an already appropriately scaled number is interpolated to provide numerical input, the unit scale indicator u may need to be appended to prevent an additional inappropriate default scaling. The number, N, may be specified in decimal-fraction form but the parameter finally stored is rounded to an integer number of basic units.
The absolute position indicator ~ may be prepended to a number N to generate the distance to the vertical or horizontal place N. For vertically-oriented requests and functions, ~N becomes the distance in basic units from the current vertical place on the page or in a diversion (§7.4) to the the vertical place N. For all other requests and functions, ~N becomes the distance from the current horizontal place on the input line to the horizontal place N. For example,
.sp ~3.2c
will space in the required direction to 3.2centimeters from the top of the page.
22.4.Numerical expressions. Wherever numerical input is expected an expression involving parentheses, the arithmetic operators +, -, /, *, % (mod), and the logical operators <, >, <=, >=, = (or ==), & (and), : (or) may be used. Except where controlled by parentheses, evaluation of expressions is left-to-right; there is no operator precedence. In the case of certain requests, an initial + or - is stripped and interpreted as an increment or decrement indicator respectively. In the presence of default scaling, the desired scale indicator must be attached to every number in an expression for which the desired and default scaling differ. For example, if the number register x contains 2 and the current point size is 10, then

.ll (4.25i+\nxP+3)/2u
will set the line length to 1/2 the sum of 4.25 inches + 2 picas + 30 points.
22.5.Notation. Numerical parameters are indicated in this manual in two ways. ±N means that the argument may take the forms N, +N, or -N and that the corresponding effect is to set the affected parameter to N, to increment it by N, or to decrement it by N respectively. Plain N means that an initial algebraic sign is not an increment indicator, but merely the sign of N. Generally, unreasonable numerical input is either ignored or truncated to a reasonable value. For example, most requests expect to set parameters to non-negative values; exceptions are sp, wh, ch, nr, and if. The requests ps, ft, po, vs, ls, ll, in, and lt restore the previous parameter value in the absence of an argument.
Single character arguments are indicated by single lower case letters and one/two character arguments are indicated by a pair of lower case letters. Character string arguments are indicated by multi-character mnemonics.
23. Font and Character Size Control
23.1.Character set. The TROFF character set consists of the Graphics Systems Commercial|II character set plus a Special Mathematical Font character set--each having 102 characters. These character sets are shown in the attached Table|I. All ASCII characters are included, with some on the Special Font. With three exceptions, the ASCII characters are input as themselves, and non-ASCII characters are input in the form \(xx where xx is a two-character name given in the attached Table|II. The three ASCII exceptions are mapped as follows:

center box; cs|cs cc|cc cl|cl. ASCII Input Printed by TROFF Character Name Character Name _ ' acute accent ' close quote ` grave accent ` open quote - minus - hyphen

The characters ', `, and - may be input by \', \`, and \- respectively or by their names (Table II). The ASCII characters @, #, ", ', `, <, >, \, {, }, ~, ^, and _ exist only on the Special Font and are printed as a 1-em space if that Font is not mounted.
NROFF understands the entire TROFF character set, but can in general print only ASCII characters, additional characters as may be available on the output device, such characters as may be able to be constructed by overstriking or other combination, and those that can reasonably be mapped into other printable characters. The exact behavior is determined by a driving table prepared for each device. The characters ', `, and _ print as themselves.
23.2.Fonts. The default mounted fonts are Times Roman (R), Times Italic (I), Times Bold (B), and the Special Mathematical Font (S) on physical typesetter positions 1, 2, 3, and 4 respectively. These fonts are used in this document. The current font, initially Roman, may be changed (among the mounted fonts) by use of the ft request, or by imbedding at any desired point either \fx, \f(xx, or \fN where x and xx are the name of a mounted font and N is a numerical font position. It is not necessary to change to the Special font; characters on that font are automatically handled. A request for a named but not-mounted font is ignored. TROFF can be informed that any particular font is mounted by use of the fp request. The list of known fonts is installation dependent. In the subsequent discussion of font-related requests, F represents either a one/two-character font name or the numerical font position, 1-4. The current font is available (as numerical position) in the read-only number register .f.
NROFF understands font control and normally underlines Italic characters (see §10.5).
23.3.Character size. Character point sizes available on the Graphic Systems typesetter are 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 28, and 36. This is a range of 1/12 inch to 1/2 inch. The ps request is used to change or restore the point size. Alternatively the point size may be changed between any two characters by imbedding a \sN at the desired point to set the size to N, or a \s±N (1<=N<=9) to increment/decrement the size by N; \s0 restores the previous size. Requested point size values that are between two valid sizes yield the larger of the two. The current size is available in the .s register. NROFF ignores type size control.
Request Initial If No
Form Value Argument Notes* Explanation

*Notes are explained at the end of the Summary and Index above.

&ps|±N 10point previous E Point size set to ±N. Alternatively imbed \sN or \s±N. Any positive size value may be requested; if invalid, the next larger valid size will result, with a maximum of 36. A paired sequence +N,-N will work because the previous requested value is also remembered. Ignored in NROFF.
&ss|N 12/36em ignored E Space-character size is set to N/36ems. This size is the minimum word spacing in adjusted text. Ignored in NROFF.
&csFNM off - P Constant character space (width) mode is set on for font F (if mounted); the width of every character will be taken to be N/36 ems. If M is absent, the em is that of the character's point size; if M is given, the em is M-points. All affected characters are centered in this space, including those with an actual width larger than this space. Special Font characters occurring while the current font is F are also so treated. If N is absent, the mode is turned off. The mode must be still or again in effect when the characters are physically printed. Ignored in NROFF.
&bd|F|N off - P The characters in font F will be artificially emboldened by printing each one twice, separated by N-1 basic units. A reasonable value for N is 3 when the character size is in the vicinity of 10 points. If N is missing the embolden mode is turned off. The column heads above were printed with .bd|I|3. The mode must be still or again in effect when the characters are physically printed. Ignored in NROFF.
&bd|S|F|N off - P The characters in the Special Font will be emboldened whenever the current font is F. This manual was printed with .bdSB3. The mode must be still or again in effect when the characters are physically printed.
&ft|F Roman previous E Font changed to F. Alternatively, imbed \fF. The font name P is reserved to mean the previous font.
&fp|N|F R,I,B,S ignored - Font position. This is a statement that a font named F is mounted on position N (1-4). It is a fatal error if F is not known. The phototypesetter has four fonts physically mounted. Each font consists of a film strip which can be mounted on a numbered quadrant of a wheel. The default mounting sequence assumed by TROFF is R, I, B, and S on positions 1, 2, 3 and 4.
24. Page control
Top and bottom margins are not automatically provided; it is conventional to define two macros and to set traps for them at vertical positions 0 (top) and -N (N from the bottom). See §7 and Tutorial Examples §T2. A pseudo-page transition onto the first page occurs either when the first break occurs or when the first non-diverted text processing occurs. Arrangements for a trap to occur at the top of the first page must be completed before this transition. In the following, references to the current diversion (§7.4) mean that the mechanism being described works during both ordinary and diverted output (the former considered as the top diversion level).
The useable page width on the Graphic Systems phototypesetter is about 7.54|inches, beginning about 1/27|inch from the left edge of the 8|inch wide, continuous roll paper. The physical limitations on NROFF output are output-device dependent.
Request Initial If No
Form Value Argument Notes Explanation

&pl|±N 11in 11in v Page length set to ±N. The internal limitation is about 75|inches in TROFF and about 136|inches in NROFF. The current page length is available in the .p register.
&bp|±N N=1 - B*,v Begin page.
*The use of " ' " as control character (instead of ".") suppresses the break function.
The current page is ejected and a new page is begun. If ±N is given, the new page number will be ±N. Also see request ns.
&pn|±N N=1 ignored - Page number. The next page (when it occurs) will have the page number ±N. A pn must occur before the initial pseudo-page transition to effect the page number of the first page. The current page number is in the % register.
&po|±N 0;|26/27in** previous v Page offset.
**Values separated by ";" are for NROFF and TROFF respectively.
The current left margin is set to ±N. The TROFF initial value provides about 1|inch of paper margin including the physical typesetter margin of 1/27|inch. In TROFF the maximum (line-length)+(page-offset) is about 7.54 inches. See §6. The current page offset is available in the .o register.
&ne|N - N=1V D,v Need N vertical space. If the distance, D, to the next trap position (see §7.5) is less than N, a forward vertical space of size D occurs, which will spring the trap. If there are no remaining traps on the page, D is the distance to the bottom of the page. If D<V, another line could still be output and spring the trap. In a diversion, D is the distance to the diversion trap, if any, or is very large.
&mk|R none internal D Mark the current vertical place in an internal register (both associated with the current diversion level), or in register R, if given. See rt request.
&rt|±N none internal D,v Return upward only to a marked vertical place in the current diversion. If ±N (w.r.t. current place) is given, the place is ±N from the top of the page or diversion or, if N is absent, to a place marked by a previous mk. Note that the sp request (§5.3) may be used in all cases instead of rt by spacing to the absolute place stored in a explicit register; e.|g. using the sequence .mk|R ... .sp|~\nRu.
25. Text Filling, Adjusting, and Centering
25.1.Filling and adjusting. Normally, words are collected from input text lines and assembled into a output text line until some word doesn't fit. An attempt is then made the hyphenate the word in effort to assemble a part of it into the output line. The spaces between the words on the output line are then increased to spread out the line to the current line length minus any current indent. A word is any string of characters delimited by the space character or the beginning/end of the input line. Any adjacent pair of words that must be kept together (neither split across output lines nor spread apart in the adjustment process) can be tied together by separating them with the unpaddable space character "\ " (backslash-space). The adjusted word spacings are uniform in TROFF and the minimum interword spacing can be controlled with the ss request (§2). In NROFF, they are normally nonuniform because of quantization to character-size spaces; however, the command line option -e causes uniform spacing with full output device resolution. Filling, adjustment, and hyphenation (§13) can all be prevented or controlled. The text length on the last line output is available in the .n register, and text base-line position on the page for this line is in the nl register. The text base-line high-water mark (lowest place) on the current page is in the .h register.
An input text line ending with ., ?, or ! is taken to be the end of a sentence, and an additional space character is automatically provided during filling. Multiple inter-word space characters found in the input are retained, except for trailing spaces; initial spaces also cause a break.
When filling is in effect, a \p may be imbedded or attached to a word to cause a break at the end of the word and have the resulting output line spread out to fill the current line length.
A text input line that happens to begin with a control character can be made to not look like a control line by prefacing it with the non-printing, zero-width filler character \&. Still another way is to specify output translation of some convenient character into the control character using tr (§10.5).
25.2.Interrupted text. The copying of a input line in nofill(non-fill) mode can be interrupted by terminating the partial line with a \c. The next encountered input text line will be considered to be a continuation of the same line of input text. Similarly, a word within filled text may be interrupted by terminating the word (and line) with \c; the next encountered text will be taken as a continuation of the interrupted word. If the intervening control lines cause a break, any partial line will be forced out along with any partial word.
Request Initial If No
Form Value Argument Notes Explanation

&br - - B Break. The filling of the line currently being collected is stopped and the line is output without adjustment. Text lines beginning with space characters and empty text lines (blank lines) also cause a break.
&fi fill|on - B,E Fill subsequent output lines. The register .u is 1 in fill mode and 0 in nofill mode.
&nf fill|on - B,E Nofill. Subsequent output lines are neither filled nor adjusted. Input text lines are copied directly to output lines without regard for the current line length.
&ad|c adj,both adjust E Line adjustment is begun. If fill mode is not on, adjustment will be deferred until fill mode is back on. If the type indicator c is present, the adjustment type is changed as shown in the following table.

center box; c|c c|l. Indicator Adjust Type _ l adjust left margin only r adjust right margin only c center b or n adjust both margins absent unchanged

&na adjust - E Noadjust. Adjustment is turned off; the right margin will be ragged. The adjustment type for ad is not changed. Output line filling still occurs if fill mode is on.
&ce|N off N=1 B,E Center the next N input text lines within the current (line-length minus indent). If N=0, any residual count is cleared. A break occurs after each of the N input lines. If the input line is too long, it will be left adjusted.
26. Vertical Spacing
26.1.Base-line spacing. The vertical spacing (V) between the base-lines of successive output lines can be set using the vs request with a resolution of 1/144inch=1/2|point in TROFF, and to the output device resolution in NROFF. V must be large enough to accommodate the character sizes on the affected output lines. For the common type sizes (9-12 points), usual typesetting practice is to set V to 2 points greater than the point size; TROFF default is 10-point type on a 12-point spacing (as in this document). The current V is available in the .v register. Multiple-V line separation (e.g. double spacing) may be requested with ls.
26.2.Extra line-space. If a word contains a vertically tall construct requiring the output line containing it to have extra vertical space before and/or after it, the extra-line-space function \x'N' can be imbedded in or attached to that word. In this and other functions having a pair of delimiters around their parameter (here '), the delimiter choice is arbitrary, except that it can't look like the continuation of a number expression for N. If N is negative, the output line containing the word will be preceded by N extra vertical space; if N is positive, the output line containing the word will be followed by N extra vertical space. If successive requests for extra space apply to the same line, the maximum values are used. The most recently utilized post-line extra line-space is available in the .a register.
26.3.Blocks of vertical space. A block of vertical space is ordinarily requested using sp, which honors the no-space mode and which does not space past a trap. A contiguous block of vertical space may be reserved using sv.
Request Initial If No
Form Value Argument Notes Explanation

&vsN 1/6in;12pts previous E,p Set vertical base-line spacing size V. Transient extra vertical space available with \x'N' (see above).
&lsN N=1 previous E Line spacing set to ±N. N-1 Vs (blank lines) are appended to each output text line. Appended blank lines are omitted, if the text or previous appended blank line reached a trap position.
&sp|N - N=1V B,v Space vertically in either direction. If N is negative, the motion is backward (upward) and is limited to the distance to the top of the page. Forward (downward) motion is truncated to the distance to the nearest trap. If the no-space mode is on, no spacing occurs (see ns, and rs below).
&sv|N - N=1V v Save a contiguous vertical block of size N. If the distance to the next trap is greater than N, N vertical space is output. No-space mode has no effect. If this distance is less than N, no vertical space is immediately output, but N is remembered for later output (see os). Subsequent sv requests will overwrite any still remembered N.
&os - - - Output saved vertical space. No-space mode has no effect. Used to finally output a block of vertical space requested by an earlier sv request.
&ns space - D No-space mode turned on. When on, the no-space mode inhibits sp requests and bp requests without a next page number. The no-space mode is turned off when a line of output occurs, or with rs.
&rs space - D Restore spacing. The no-space mode is turned off.
Blank|text|line. - B Causes a break and output of a blank line exactly like sp|1.

27. Line Length and Indenting
The maximum line length for fill mode may be set with ll. The indent may be set with in; an indent applicable to only the next output line may be set with ti. The line length includes indent space but not page offset space. The line-length minus the indent is the basis for centering with ce. The effect of ll, in, or ti is delayed, if a partially collected line exists, until after that line is output. In fill mode the length of text on an output line is less than or equal to the line length minus the indent. The current line length and indent are available in registers .l and .i respectively. The length of three-part titles produced by tl (see §14) is independently set by lt.
Request Initial If No
Form Value Argument Notes Explanation

&ll|±N 6.5in previous E,m Line length is set to ±N. In TROFF the maximum (line-length)+(page-offset) is about 7.54 inches.
&in|±N N=0 previous B,E,m Indent is set to ±N. The indent is prepended to each output line.
&ti|±N - ignored B,E,m Temporary indent. The next output text line will be indented a distance ±N with respect to the current indent. The resulting total indent may not be negative. The current indent is not changed.
28. Macros, Strings, Diversion, and Position Traps
28.1.Macros and strings. A macro is a named set of arbitrary lines that may be invoked by name or with a trap. A string is a named string of characters, not including a newline character, that may be interpolated by name at any point. Request, macro, and string names share the same name list. Macro and string names may be one or two characters long and may usurp previously defined request, macro, or string names. Any of these entities may be renamed with rn or removed with rm. Macros are created by de and di, and appended to by am and da; di and da cause normal output to be stored in a macro. Strings are created by ds and appended to by as. A macro is invoked in the same way as a request; a control line beginning .xx will interpolate the contents of macro xx. The remainder of the line may contain up to nine arguments. The strings x and xx are interpolated at any desired point with \*x and \*(xx respectively. String references and macro invocations may be nested.
28.2.Copy mode input interpretation. During the definition and extension of strings and macros (not by diversion) the input is read in copy mode. The input is copied without interpretation except that:
+ The contents of number registers indicated by \n are interpolated.
+ Strings indicated by \* are interpolated.
+ Arguments indicated by \$ are interpolated.
+ Concealed newlines indicated by \(newline) are eliminated.
+ Comments indicated by \" are eliminated.
+ \t and \a are interpreted as ASCII horizontal tab and SOH respectively (§9).
+ \\ is interpreted as \.
+ \. is interpreted as ".".
These interpretations can be suppressed by prepending a \. For example, since \\ maps into a \, \\n will copy as \n which will be interpreted as a number register indicator when the macro or string is reread.
28.3.Arguments. When a macro is invoked by name, the remainder of the line is taken to contain up to nine arguments. The argument separator is the space character, and arguments may be surrounded by double-quotes to permit imbedded space characters. Pairs of double-quotes may be imbedded in double-quoted arguments to represent a single double-quote. If the desired arguments won't fit on a line, a concealed newline may be used to continue on the next line.
When a macro is invoked the input level is pushed down and any arguments available at the previous level become unavailable until the macro is completely read and the previous level is restored. A macro's own arguments can be interpolated at any point within the macro with \$N, which interpolates the Nth argument (1<=N<=9). If an invoked argument doesn't exist, a null string results. For example, the macro xx may be defined by
&de xx \"begin definition
Today is \\$1 the \\$2.
&. \"end definition
and called by
&xx Monday 14th
to produce the text
Today is Monday the 14th.
Note that the \$ was concealed in the definition with a prepended \. The number of currently available arguments is in the .$ register.
No arguments are available at the top (non-macro) level in this implementation. Because string referencing is implemented as a input-level push down, no arguments are available from within a string. No arguments are available within a trap-invoked macro.
Arguments are copied in copy mode onto a stack where they are available for reference. The mechanism does not allow an argument to contain a direct reference to a long string (interpolated at copy time) and it is advisable to conceal string references (with an extra \) to delay interpolation until argument reference time.
28.4.Diversions. Processed output may be diverted into a macro for purposes such as footnote processing (see Tutorial §T5) or determining the horizontal and vertical size of some text for conditional changing of pages or columns. A single diversion trap may be set at a specified vertical position. The number registers dn and dl respectively contain the vertical and horizontal size of the most recently ended diversion. Processed text that is diverted into a macro retains the vertical size of each of its lines when reread in nofill mode regardless of the current V. Constant-spaced (cs) or emboldened (bd) text that is diverted can be reread correctly only if these modes are again or still in effect at reread time. One way to do this is to imbed in the diversion the appropriate cs or bd requests with the transparent mechanism described in §10.6.
Diversions may be nested and certain parameters and registers are associated with the current diversion level (the top non-diversion level may be thought of as the 0th diversion level). These are the diversion trap and associated macro, no-space mode, the internally-saved marked place (see mk and rt), the current vertical place (.d register), the current high-water text base-line (.h register), and the current diversion name (.z register).
28.5.Traps. Three types of trap mechanisms are available--page traps, a diversion trap, and an input-line-count trap. Macro-invocation traps may be planted using wh at any page position including the top. This trap position may be changed using ch. Trap positions at or below the bottom of the page have no effect unless or until moved to within the page or rendered effective by an increase in page length. Two traps may be planted at the same position only by first planting them at different positions and then moving one of the traps; the first planted trap will conceal the second unless and until the first one is moved (see Tutorial Examples §T5). If the first one is moved back, it again conceals the second trap. The macro associated with a page trap is automatically invoked when a line of text is output whose vertical size reaches or sweeps past the trap position. Reaching the bottom of a page springs the top-of-page trap, if any, provided there is a next page. The distance to the next trap position is available in the .t register; if there are no traps between the current position and the bottom of the page, the distance returned is the distance to the page bottom.
A macro-invocation trap effective in the current diversion may be planted using dt. The .t register works in a diversion; if there is no subsequent trap a large distance is returned. For a description of input-line-count traps, see it below.
Request Initial If No
Form Value Argument Notes Explanation

&de|xx|yy - .yy=.. - Define or redefine the macro xx. The contents of the macro begin on the next input line. Input lines are copied in copy mode until the definition is terminated by a line beginning with .yy, whereupon the macro yy is called. In the absence of yy, the definition is terminated by a line beginning with "..". A macro may contain de requests provided the terminating macros differ or the contained definition terminator is concealed. ".." can be concealed as \\.. which will copy as \.. and be reread as "..".
&am|xx|yy - .yy=.. - Append to macro (append version of de).
&ds|xx|string - ignored - Define a string xx containing string. Any initial double-quote in string is stripped off to permit initial blanks.
&as|xx|string - ignored - Append string to string xx (append version of ds).
&rm|xx - ignored - Remove request, macro, or string. The name xx is removed from the name list and any related storage space is freed. Subsequent references will have no effect.
&rn|xx|yy - ignored - Rename request, macro, or string xx to yy. If yy exists, it is first removed.
&di|xx - end D Divert output to macro xx. Normal text processing occurs during diversion except that page offsetting is not done. The diversion ends when the request di or da is encountered without an argument; extraneous requests of this type should not appear when nested diversions are being used.
&da|xx - end D Divert, appending to xx (append version of di).
&wh|N|xx - - v Install a trap to invoke xx at page position N; a negative N will be interpreted with respect to the page bottom. Any macro previously planted at N is replaced by xx. A zero N refers to the top of a page. In the absence of xx, the first found trap at N, if any, is removed.
&ch|xx|N - - v Change the trap position for macro xx to be N. In the absence of N, the trap, if any, is removed.
&dt|N|xx - off D,v Install a diversion trap at position N in the current diversion to invoke macro xx. Another dt will redefine the diversion trap. If no arguments are given, the diversion trap is removed.
&it|N|xx - off E Set an input-line-count trap to invoke the macro xx after N lines of text input have been read (control or request lines don't count). The text may be in-line text or text interpolated by inline or trap-invoked macros.
&em|xx none none - The macro xx will be invoked when all input has ended. The effect is the same as if the contents of xx had been at the end of the last file processed.
29. Number Registers
A variety of parameters are available to the user as predefined, named number registers (see Summary and Index, page 7). In addition, the user may define his own named registers. Register names are one or two characters long and do not conflict with request, macro, or string names. Except for certain predefined read-only registers, a number register can be read, written, automatically incremented or decremented, and interpolated into the input in a variety of formats. One common use of user-defined registers is to automatically number sections, paragraphs, lines, etc. A number register may be used any time numerical input is expected or desired and may be used in numerical expressions (§1.4).
Number registers are created and modified using nr, which specifies the name, numerical value, and the auto-increment size. Registers are also modified, if accessed with an auto-incrementing sequence. If the registers x and xx both contain N and have the auto-increment size M, the following access sequences have the effect shown:

center box; c2|c2|c c2|c2|c2 l2|c2|c2 l2|c2|c2 l2|l2|c2. Effect on Value Sequence Register Interpolated _ \nx none N \n(xx none N \n+x x incremented by M N+M \n-x x decremented by M N-M \n+(xx xx incremented by M N+M \n-(xx xx decremented by M N-M

When interpolated, a number register is converted to decimal (default), decimal with leading zeros, lower-case Roman, upper-case Roman, lower-case sequential alphabetic, or upper-case sequential alphabetic according to the format specified by af.
Request Initial If No
Form Value Argument Notes Explanation

&nr|R|±N|M - u The number register R is assigned the value ±N with respect to the previous value, if any. The increment for auto-incrementing is set to M.
&af|R|c arabic - - Assign format c to register R. The available formats are:

center box; c2|c c2|c c2|l. Numbering Format Sequence _ 1 0,1,2,3,4,5,... 001 000,001,002,003,004,005,... i 0,i,ii,iii,iv,v,... I 0,I,II,III,IV,V,... a 0,a,b,c,...,z,aa,ab,...,zz,aaa,... A 0,A,B,C,...,Z,AA,AB,...,ZZ,AAA,...

An arabic format having N digits specifies a field width of N digits (example 2 above). The read-only registers and the width function (§11.2) are always arabic.
&rr|R - ignored - Remove register R. If many registers are being created dynamically, it may become necessary to remove no longer used registers to recapture internal storage space for newer registers.
30. Tabs, Leaders, and Fields
30.1.Tabs and leaders. The ASCII horizontal tab character and the ASCII SOH (hereafter known as the leader character) can both be used to generate either horizontal motion or a string of repeated characters. The length of the generated entity is governed by internal tab stops specifiable with ta. The default difference is that tabs generate motion and leaders generate a string of periods; tc and lc offer the choice of repeated character or motion. There are three types of internal tab stops--left adjusting, right adjusting, and centering. In the following table: D is the distance from the current position on the input line (where a tab or leader was found) to the next tab stop; next-string consists of the input characters following the tab (or leader) up to the next tab (or leader) or end of line; and W is the width of next-string.

center box; c2|c2|c c2|c2|c c2|c2|l. Tab Length of motion or Location of type repeated characters next-string _ Left D Following D Right D-W Right adjusted within D Centered D-W/2 Centered on right end of D

The length of generated motion is allowed to be negative, but that of a repeated character string cannot be. Repeated character strings contain an integer number of characters, and any residual distance is prepended as motion. Tabs or leaders found after the last tab stop are ignored, but may be used as next-string terminators.
Tabs and leaders are not interpreted in copy mode. \t and \a always generate a non-interpreted tab and leader respectively, and are equivalent to actual tabs and leaders in copy mode.
30.2.Fields. A field is contained between a pair of field delimiter characters, and consists of sub-strings separated by padding indicator characters. The field length is the distance on the input line from the position where the field begins to the next tab stop. The difference between the total length of all the sub-strings and the field length is incorporated as horizontal padding space that is divided among the indicated padding places. The incorporated padding is allowed to be negative. For example, if the field delimiter is # and the padding indicator is ^, #^xxx^right# specifies a right-adjusted string with the string xxx centered in the remaining space.
Request Initial If No
Form Value Argument Notes Explanation

&ta|Nt|... 0.8;|0.5in none E,m Set tab stops and types. t=R, right adjusting; t=C, centering; t absent, left adjusting. TROFF tab stops are preset every 0.5in.; NROFF every 0.8in. The stop values are separated by spaces, and a value preceded by + is treated as an increment to the previous stop value.
&tc|c none none E The tab repetition character becomes c, or is removed specifying motion.
&lc|c . none E The leader repetition character becomes c, or is removed specifying motion.
&fc|a|b off off - The field delimiter is set to a; the padding indicator is set to the space character or to b, if given. In the absence of arguments the field mechanism is turned off.
31. Input and Output Conventions and Character Translations
31.1.Input character translations. Ways of inputting the graphic character set were discussed in §2.1. The ASCII control characters horizontal tab (§9.1), SOH (§9.1), and backspace (§10.3) are discussed elsewhere. The newline delimits input lines. In addition, STX, ETX, ENQ, ACK, and BEL are accepted, and may be used as delimiters or translated into a graphic with tr (§10.5). All others are ignored.
The escape character \ introduces escape sequences--causes the following character to mean another character, or to indicate some function. A complete list of such sequences is given in the Summary and Index on page 6. \ should not be confused with the ASCII control character ESC of the same name. The escape character \ can be input with the sequence \\. The escape character can be changed with ec, and all that has been said about the default \ becomes true for the new escape character. \e can be used to print whatever the current escape character is. If necessary or convenient, the escape mechanism may be turned off with eo, and restored with ec.
Request Initial If No
Form Value Argument Notes Explanation

&ec|c \ \ - Set escape character to \, or to c, if given.
&eo on - - Turn escape mechanism off.
31.2.Ligatures. Five ligatures are available in the current TROFF character set -- fi, fl, ff, ffi, and ffl. They may be input (even in NROFF) by \(fi, \(fl, \(ff, \(Fi, and \(Fl respectively. The ligature mode is normally on in TROFF, and automatically invokes ligatures during input.
Request Initial If No
Form Value Argument Notes Explanation

&lg|N off;|on on - Ligature mode is turned on if N is absent or non-zero, and turned off if N=0. If N=2, only the two-character ligatures are automatically invoked. Ligature mode is inhibited for request, macro, string, register, or file names, and in copy mode. No effect in NROFF.
31.3.Backspacing, underlining, overstriking, etc. Unless in copy mode, the ASCII backspace character is replaced by a backward horizontal motion having the width of the space character. Underlining as a form of line-drawing is discussed in §12.4. A generalized overstriking function is described in §12.1.
NROFF automatically underlines characters in the underline font, specifiable with uf, normally that on font position 2 (normally Times Italic, see §2.2). In addition to ft and \fF, the underline font may be selected by ul and cu. Underlining is restricted to an output-device-dependent subset of reasonable characters.
Request Initial If No
Form Value Argument Notes Explanation

&ul|N off N=1 E Underline in NROFF (italicize in TROFF) the next N input text lines. Actually, switch to underline font, saving the current font for later restoration; other font changes within the span of a ul will take effect, but the restoration will undo the last change. Output generated by tl (§14) is affected by the font change, but does not decrement N. If N>1, there is the risk that a trap interpolated macro may provide text lines within the span; environment switching can prevent this.
&cu|N off N=1 E A variant of ul that causes every character to be underlined in NROFF. Identical to ul in TROFF.
&uf|F Italic Italic - Underline font set to F. In NROFF, F may not be on position 1 (initially Times Roman).
31.4.Control characters. Both the control character . and the no-break control character ' may be changed, if desired. Such a change must be compatible with the design of any macros used in the span of the change, and particularly of any trap-invoked macros.
Request Initial If No
Form Value Argument Notes Explanation

&cc|c . . E The basic control character is set to c, or reset to ".".
&c2|c ' ' E The nobreak control character is set to c, or reset to "'".
31.5.Output translation. One character can be made a stand-in for another character using tr. All text processing (e. g. character comparisons) takes place with the input (stand-in) character which appears to have the width of the final character. The graphic translation occurs at the moment of output (including diversion).
Request Initial If No
Form Value Argument Notes Explanation

&tr|abcd.... none - O Translate a into b, c into d, etc. If an odd number of characters is given, the last one will be mapped into the space character. To be consistent, a particular translation must stay in effect from input to output time.
31.6.Transparent throughput. An input line beginning with a \! is read in copy mode and transparently output (without the initial \!); the text processor is otherwise unaware of the line's presence. This mechanism may be used to pass control information to a post-processor or to imbed control lines in a macro created by a diversion.
31.7.Comments and concealed newlines. An uncomfortably long input line that must stay one line (e. g. a string definition, or nofilled text) can be split into many physical lines by ending all but the last one with the escape \. The sequence \(newline) is always ignored--except in a comment. Comments may be imbedded at the end of any line by prefacing them with \". The newline at the end of a comment cannot be concealed. A line beginning with \" will appear as a blank line and behave like .sp|1; a comment can be on a line by itself by beginning the line with .\".
32. Local Horizontal and Vertical Motions, and the Width Function
32.1.Local Motions. The functions \v'N' and \h'N' can be used for local vertical and horizontal motion respectively. The distance N may be negative; the positive directions are rightward and downward. A local motion is one contained within a line. To avoid unexpected vertical dislocations, it is necessary that the net vertical local motion within a word in filled text and otherwise within a line balance to zero. The above and certain other escape sequences providing local motion are summarized in the following table.

center box; c2|cs2||c2|cs2 c1|c2c2||c2|c2c2. Vertical Effect in Horizontal Effect in Local Motion TROFF NROFF Local Motion TROFF NROFF _ l2|ls2||l2|ls2. \v'N' Move distance N \h'N' Move distance N _2|_2_2||l2|ls2. x x x \(space) Unpaddable space-size space l2|l2|l2||l2|ls2. \u ½ em up ½ line up \0 Digit-size space l2|l2|l2||_2|_2_2. \d ½ em down ½ line down x x x l2|l2|l2||l2|l2|l2. \r 1 em up 1 line up \| 1/6 em space ignored \^ 1/12 em space ignored

As an example, E2 could be generated by the sequence E\s-2\v'-0.4m'2\v'0.4m'\s+2; it should be noted in this example that the 0.4|em vertical motions are at the smaller size.
32.2.Width Function. The width function \w'string' generates the numerical width of string (in basic units). Size and font changes may be safely imbedded in string, and will not affect the current environment. For example, .ti|-\w'1.|'u could be used to temporarily indent leftward a distance equal to the size of the string "1.|".
The width function also sets three number registers. The registers st and sb are set respectively to the highest and lowest extent of string relative to the baseline; then, for example, the total height of the string is \n(stu-\n(sbu. In TROFF the number register ct is set to a value between 0|and|3: 0 means that all of the characters in string were short lower case characters without descenders (like e); 1 means that at least one character has a descender (like y); 2 means that at least one character is tall (like H); and 3 means that both tall characters and characters with descenders are present.
32.3.Mark horizontal place. The escape sequence \kx will cause the current horizontal position in the input line to be stored in register x. As an example, the construction \kxword\h'~\nxu+2u'word will embolden word by backing up to almost its beginning and overprinting it, resulting in wordword.
33. Overstrike, Bracket, Line-drawing, and Zero-width Functions
33.1.Overstriking. Automatically centered overstriking of up to nine characters is provided by the overstrike function \o'string'. The characters in string overprinted with centers aligned; the total width is that of the widest character. string should not contain local vertical motion. As examples, \o'e\'' produces e', and \o'\(mo\(sl' produces \(mo/.
33.2.Zero-width characters. The function \zc will output c without spacing over it, and can be used to produce left-aligned overstruck combinations. As examples, \z\(ci\(pl will produce O+, and \(br\z\(rn\(ul\(br will produce the smallest possible constructed box |\(rn_|.
33.3.Large Brackets. The Special Mathematical Font contains a number of bracket construction pieces (\(lt\(lb\(rt\(rb\(lk\(rk|\(lf\(rf\(lc\(rc) that can be combined into various bracket styles. The function \b'string' may be used to pile up vertically the characters in string (the first character on top and the last at the bottom); the characters are vertically separated by 1|em and the total pile is centered 1/2em above the current baseline (½ line in NROFF). For example, \b'\(lc\(lf'E\~\b'\(rc\(rf'\x'-0.5m'\x'0.5m' produces xxbEb.
33.4.Line drawing. The function \l'Nc' will draw a string of repeated c's towards the right for a distance N. (\l is \(lower case L). If c looks like a continuation of an expression for N, it may insulated from N with a \&. If c is not specified, the _ (baseline rule) is used (underline character in NROFF). If N is negative, a backward horizontal motion of size N is made before drawing the string. Any space resulting from N/(size of c) having a remainder is put at the beginning (left end) of the string. In the case of characters that are designed to be connected such as baseline-rule _, underrule _, and root-en \(rn, the remainder space is covered by over-lapping. If N is less than the width of c, a single c is centered on a distance N. As an example, a macro to underscore a string can be written

&de us
or one to draw a box around a string
&de bx
such that
&ul "underlined words"
&bx "words in a box"
yield underlined words and |words in a box| .
The function \L'Nc' will draw a vertical line consisting of the (optional) character c stacked vertically apart 1em (1 line in NROFF), with the first two characters overlapped, if necessary, to form a continuous line. The default character is the box rule ||| (\(br); the other suitable character is the bold vertical | (\(bv). The line is begun without any initial motion relative to the current base line. A positive N specifies a line drawn downward and a negative N specifies a line drawn upward. After the line is drawn no compensating motions are made; the instantaneous baseline is at the end of the line.
The horizontal and vertical line drawing functions may be used in combination to produce large boxes. The zero-width box-rule and the ½-em wide underrule were designed to form corners when using 1-em vertical spacings. For example the macro
.de eb
.sp -1 \"compensate for next automatic base-line spacing
.nf \"avoid possibly overflowing word buffer
\h'-.5n'\L'|\\nau-1'\l'\\n(.lu+1n\(ul'\L'-|\\nau+1'\l'|0u-.5n\(ul' \"draw box
will draw a box around some text whose beginning vertical place was saved in number register a (e. g. using .mk|a) as done for this paragraph. L

34. Hyphenation.
The automatic hyphenation may be switched off and on. When switched on with hy, several variants may be set. A hyphenation indicator character may be imbedded in a word to specify desired hyphenation points, or may be prepended to suppress hyphenation. In addition, the user may specify a small exception word list.
Only words that consist of a central alphabetic string surrounded by (usually null) non-alphabetic strings are considered candidates for automatic hyphenation. Words that were input containing hyphens (minus), em-dashes (\(em), or hyphenation indicator characters--such as mother-in-law--are always subject to splitting after those characters, whether or not automatic hyphenation is on or off.
Request Initial If No
Form Value Argument Notes Explanation

&nh hyphenate - E Automatic hyphenation is turned off.
&hyN on,N=1 on,N=1 E Automatic hyphenation is turned on for N>=1, or off for N=0. If N=2, last lines (ones that will cause a trap) are not hyphenated. For N=4 and 8, the last and first two characters respectively of a word are not split off. These values are additive; i.|e. N=14 will invoke all three restrictions.
&hc|c \% \% E Hyphenation indicator character is set to c or to the default \%. The indicator does not appear in the output.
&hw|word1|... ignored - Specify hyphenation points in words with imbedded minus signs. Versions of a word with terminal s are implied; i.|e. dig-it implies dig-its. This list is examined initially and after each suffix stripping. The space available is small--about 128 characters.
35. Three Part Titles.
The titling function tl provides for automatic placement of three fields at the left, center, and right of a line with a title-length specifiable with lt. tl may be used anywhere, and is independent of the normal text collecting process. A common use is in header and footer macros.
Request Initial If No
Form Value Argument Notes Explanation

&tl|'left'center'right' - - The strings left, center, and right are respectively left-adjusted, centered, and right-adjusted in the current title-length. Any of the strings may be empty, and overlapping is permitted. If the page-number character (initially %) is found within any of the fields it is replaced by the current page number having the format assigned to register %. Any character may be used as the string delimiter.
&pc|c % off - The page number character is set to c, or removed. The page-number register remains %.
&lt|±N 6.5in previous E,m Length of title set to ±N. The line-length and the title-length are independent. Indents do not apply to titles; page-offsets do.
36. Output Line Numbering.
Automatic sequence numbering of output lines may be requested with nm. When in effect, a three-digit, arabic number plus a digit-space is prepended to output text lines. The text lines are thus offset by four digit-spaces, and otherwise retain their line length; a reduction in line length may be desired to keep the right margin aligned with an earlier margin. Blank lines, other vertical spaces, and lines generated by tl are not numbered. Numbering can be temporarily suspended with nn, or with an .nm followed by a later .nm|+0. In addition, a line number indent I, and the number-text separation S may be specified in digit-spaces. Further, it can be specified that only those line numbers that are multiples of some number M are to be printed (the others will appear as blank number fields).

Request Initial If No
Form Value Argument Notes Explanation

&nm|±N|M|S|I off E Line number mode. If ±N is given, line numbering is turned on, and the next output line numbered is numbered ±N. Default values are M=1, S=1, and I=0. Parameters corresponding to missing arguments are unaffected; a non-numeric argument is considered missing. In the absence of all arguments, numbering is turned off; the next line number is preserved for possible further use in number register ln.
&nn|N - N=1 E The next N text output lines are not numbered.
As an example, the paragraph portions of this section are numbered with M=3: .nm|1|3 was placed at the beginning; .nm was placed at the end of the first paragraph; and .nm|+0 was placed in front of this paragraph; and .nm finally placed at the end. Line lengths were also changed (by \w'0000'u) to keep the right side aligned. Another example is .nm|+5|5|x|3 which turns on numbering with the line number of the next line to be 5 greater than the last numbered line, with M=5, with spacing S untouched, and with the indent I set to 3.

37. Conditional Acceptance of Input
In the following, c is a one-character, built-in condition name, ! signifies not, N is a numerical expression, string1 and string2 are strings delimited by any non-blank, non-numeric character not in the strings, and anything represents what is conditionally accepted.
Request Initial If No
Form Value Argument Notes Explanation

&if|c|anything - - If condition c true, accept anything as input; in multi-line case use \{anything\}.
&if|!c|anything - - If condition c false, accept anything.
&if|N|anything - u If expression N > 0, accept anything.
&if|!N|anything - u If expression N <= 0, accept anything.
&if|'string1'string2'|anything - If string1 identical to string2, accept anything.
&if|!'string1'string2'|anything - If string1 not identical to string2, accept anything.
&ie|c|anything - u If portion of if-else; all above forms (like if).
&el|anything - - Else portion of if-else.
The built-in condition names are:

center box; c2|c2 c2|c2 c2|l2. Condition Name True If _ o Current page number is odd e Current page number is even t Formatter is TROFF n Formatter is NROFF

If the condition c is true, or if the number N is greater than zero, or if the strings compare identically (including motions and character size and font), anything is accepted as input. If a ! precedes the condition, number, or string comparison, the sense of the acceptance is reversed.
Any spaces between the condition and the beginning of anything are skipped over. The anything can be either a single input line (text, macro, or whatever) or a number of input lines. In the multi-line case, the first line must begin with a left delimiter \{ and the last line must end with a right delimiter \}.
The request ie (if-else) is identical to if except that the acceptance state is remembered. A subsequent and matching el (else) request then uses the reverse sense of that state. ie|-|el pairs may be nested.
Some examples are:
&if e .tl 'Even Page %'''
which outputs a title if the page number is even; and
&ie \n%>1 \{\
'sp 0.5i
&tl 'Page %'''
'sp ~1.2i|\}
&el .sp ~2.5i
which treats page 1 differently from other pages.
38. Environment Switching.
A number of the parameters that control the text processing are gathered together into an environment, which can be switched by the user. The environment parameters are those associated with requests noting E in their Notes column; in addition, partially collected lines and words are in the environment. Everything else is global; examples are page-oriented parameters, diversion-oriented parameters, number registers, and macro and string definitions. All environments are initialized with default parameter values.
Request Initial If No
Form Value Argument Notes Explanation

&ev|N N=0 previous - Environment switched to environment 0<=N<=2. Switching is done in push-down fashion so that restoring a previous environment must be done with .ev rather than specific reference.
39. Insertions from the Standard Input
The input can be temporarily switched to the system standard input with rd, which will switch back when two newlines in a row are found (the extra blank line is not used). This mechanism is intended for insertions in form-letter-like documentation. On UNIX, the standard input can be the user's keyboard, a pipe, or a file.
Request Initial If No
Form Value Argument Notes Explanation

&rd|prompt - prompt=BEL - Read insertion from the standard input until two newlines in a row are found. If the standard input is the user's keyboard, prompt (or a BEL) is written onto the user's terminal. rd behaves like a macro, and arguments may be placed after prompt.
&ex - - - Exit from NROFF/TROFF. Text processing is terminated exactly as if all input had ended.
If insertions are to be taken from the terminal keyboard while output is being printed on the terminal, the command line option -q will turn off the echoing of keyboard input and prompt only with BEL. The regular input and insertion input cannot simultaneously come from the standard input.
As an example, multiple copies of a form letter may be prepared by entering the insertions for all the copies in one file to be used as the standard input, and causing the file containing the letter to reinvoke itself using nx (§19); the process would ultimately be ended by an ex in the insertion file.
40. Input/Output File Switching
Request Initial If No
Form Value Argument Notes Explanation

&so|filename - - Switch source file. The top input (file reading) level is switched to filename. The effect of an so encountered in a macro is not felt until the input level returns to the file level. When the new file ends, input is again taken from the original file. so's may be nested.
&nx|filename end-of-file - Next file is filename. The current file is considered ended, and the input is immediately switched to filename.
&pi|program - - Pipe output to program (NROFF only). This request must occur before any printing occurs. No arguments are transmitted to program.
41. Miscellaneous

Request Initial If No
Form Value Argument Notes Explanation

&mc|c|N - off E,m Specifies that a margin character c appear a distance N to the right of the right margin after each non-empty text line (except those produced by tl). If the output line is too-long (as can happen in nofill mode) the character will be appended to the line. If N is not given, the previous N is used; the initial N is 0.2|inches in NROFF and 1em in TROFF. The margin character used with this paragraph was a 12-point box-rule.

&tm|string - newline - After skipping initial blanks, string (rest of the line) is read in copy mode and written on the user's terminal.
&ig|yy - .yy=.. - Ignore input lines. ig behaves exactly like de (§7) except that the input is discarded. The input is read in copy mode, and any auto-incremented registers will be affected.
&pm|t - all - Print macros. The names and sizes of all of the defined macros and strings are printed on the user's terminal; if t is given, only the total of the sizes is printed. The sizes is given in blocks of 128 characters.
&fl - - B Flush output buffer. Used in interactive debugging to force output.
42. Output and Error Messages.
The output from tm, pm, and the prompt from rd, as well as various error messages are written onto UNIX's standard message output. The latter is different from the standard output, where NROFF formatted output goes. By default, both are written onto the user's terminal, but they can be independently redirected.
Various error conditions may occur during the operation of NROFF and TROFF. Certain less serious errors having only local impact do not cause processing to terminate. Two examples are word overflow, caused by a word that is too large to fit into the word buffer (in fill mode), and line overflow, caused by an output line that grew too large to fit in the line buffer; in both cases, a message is printed, the offending excess is discarded, and the affected word or line is marked at the point of truncation with a * in NROFF and a <= in TROFF. The philosophy is to continue processing, if possible, on the grounds that output useful for debugging may be produced. If a serious error occurs, processing terminates, and an appropriate message is printed. Examples are the inability to create, read, or write files, and the exceeding of certain internal limits that make future output unlikely to be useful.


T1. Introduction
Although NROFF and TROFF have by design a syntax reminiscent of earlier text processors*
*For example: P.|A.|Crisman, Ed., The Compatible Time-Sharing System, MIT Press, 1965, Section|AH9.01 (Description of RUNOFF program on MIT's CTSS system).
with the intent of easing their use, it is almost always necessary to prepare at least a small set of macro definitions to describe most documents. Such common formatting needs as page margins and footnotes are deliberately not built into NROFF and TROFF. Instead, the macro and string definition, number register, diversion, environment switching, page-position trap, and conditional input mechanisms provide the basis for user-defined implementations.
The examples to be discussed are intended to be useful and somewhat realistic, but won't necessarily cover all relevant contingencies. Explicit numerical parameters are used in the examples to make them easier to read and to illustrate typical values. In many cases, number registers would really be used to reduce the number of places where numerical information is kept, and to concentrate conditional parameter initialization like that which depends on whether TROFF or NROFF is being used.
T2. Page Margins
As discussed in §3, header and footer macros are usually defined to describe the top and bottom page margin areas respectively. A trap is planted at page position 0 for the header, and at -N (N from the page bottom) for the footer. The simplest such definitions might be
&de hd \"define header
'sp 1i
&& \"end definition
&de fo \"define footer
&& \"end definition
&wh 0 hd
&wh -1i fo

which provide blank 1|inch top and bottom margins. The header will occur on the first page, only if the definition and trap exist prior to the initial pseudo-page transition (§3). In fill mode, the output line that springs the footer trap was typically forced out because some part or whole word didn't fit on it. If anything in the footer and header that follows causes a break, that word or part word will be forced out. In this and other examples, requests like bp and sp that normally cause breaks are invoked using the no-break control character ' to avoid this. When the header/footer design contains material requiring independent text processing, the environment may be switched, avoiding most interaction with the running text.
A more realistic example would be
&de hd \"header
&if t .tl '\(rn''\(rn' \"troff cut mark
&if \\n%>1 \{\
'sp ~0.5i-1 \"tl base at 0.5i
&tl ''- % -'' \"centered page number
&ps \"restore size
&ft \"restore font
&vs \} \"restore vs
'sp ~1.0i \"space to 1.0i
&ns \"turn on no-space mode
&de fo \"footer
&ps 10 \"set footer/header size
&ft R \"set font
&vs 12p \"set base-line spacing
&if \\n%=1 \{\
'sp ~\\n(.pu-0.5i-1 \"tl base 0.5i up
&tl ''- % -'' \} \"first page number
&wh 0 hd
&wh -1i fo

which sets the size, font, and base-line spacing for the header/footer material, and ultimately restores them. The material in this case is a page number at the bottom of the first page and at the top of the remaining pages. If TROFF is used, a cut mark is drawn in the form of root-en's at each margin. The sp's refer to absolute positions to avoid dependence on the base-line spacing. Another reason for this in the footer is that the footer is invoked by printing a line whose vertical spacing swept past the trap position by possibly as much as the base-line spacing. The no-space mode is turned on at the end of hd to render ineffective accidental occurrences of sp at the top of the running text.
The above method of restoring size, font, etc. presupposes that such requests (that set previous value) are not used in the running text. A better scheme is save and restore both the current and previous values as shown for size in the following:
&de fo
&nr s1 \\n(.s \"current size
&nr s2 \\n(.s \"previous size
& --- \"rest of footer
&de hd
& --- \"header stuff
&ps \\n(s2 \"restore previous size
&ps \\n(s1 \"restore current size

Page numbers may be printed in the bottom margin by a separate macro triggered during the footer's page ejection:
&de bn \"bottom number
&tl ''- % -'' \"centered page number
&wh -0.5i-1v bn \"tl base 0.5i up

T3. Paragraphs and Headings
The housekeeping associated with starting a new paragraph should be collected in a paragraph macro that, for example, does the desired preparagraph spacing, forces the correct font, size, base-line spacing, and indent, checks that enough space remains for more than one line, and requests a temporary indent.
&de pg \"paragraph
&br \"break
&ft R \"force font,
&ps 10 \"size,
&vs 12p \"spacing,
&in 0 \"and indent
&sp 0.4 \"prespace
&ne 1+\\n(.Vu \"want more than 1 line
&ti 0.2i \"temp indent

The first break in pg will force out any previous partial lines, and must occur before the vs. The forcing of font, etc. is partly a defense against prior error and partly to permit things like section heading macros to set parameters only once. The prespacing parameter is suitable for TROFF; a larger space, at least as big as the output device vertical resolution, would be more suitable in NROFF. The choice of remaining space to test for in the ne is the smallest amount greater than one line (the .V is the available vertical resolution).
A macro to automatically number section headings might look like:
&de sc \"section
& --- \"force font, etc.
&sp 0.4 \"prespace
&ne 2.4+\\n(.Vu \"want 2.4+ lines
&nr S 0 1 \"init S

The usage is .sc, followed by the section heading text, followed by .pg. The ne test value includes one line of heading, 0.4 line in the following pg, and one line of the paragraph text. A word consisting of the next section number and a period is produced to begin the heading line. The format of the number may be set by af (§8).
Another common form is the labeled, indented paragraph, where the label protrudes left into the indent space.
&de lp \"labeled paragraph
&in 0.5i \"paragraph indent
&ta 0.2i 0.5i \"label, paragraph
&ti 0
\t\\$1\t\c \"flow into paragraph

The intended usage is ".lp label"; label will begin at 0.2inch, and cannot exceed a length of 0.3inch without intruding into the paragraph. The label could be right adjusted against 0.4inch by setting the tabs instead with .ta|0.4iR|0.5i. The last line of lp ends with \c so that it will become a part of the first line of the text that follows.
T4. Multiple Column Output
The production of multiple column pages requires the footer macro to decide whether it was invoked by other than the last column, so that it will begin a new column rather than produce the bottom margin. The header can initialize a column register that the footer will increment and test. The following is arranged for two columns, but is easily modified for more.
&de hd \"header
& ---
&nr cl 0 1 \"init column count
&mk \"mark top of text
&de fo \"footer
&ie \\n+(cl<2 \{\
&po +3.4i \"next column; 3.1+0.3
&rt \"back to mark
&ns \} \"no-space mode
&el \{\
&po \\nMu \"restore left margin
& ---
'bp \}
&ll 3.1i \"column width
&nr M \\n(.o \"save left margin

Typically a portion of the top of the first page contains full width text; the request for the narrower line length, as well as another .mk would be made where the two column output was to begin.
T5. Footnote Processing
The footnote mechanism to be described is used by imbedding the footnotes in the input text at the point of reference, demarcated by an initial .fn and a terminal .ef:
Footnote text and control lines...

In the following, footnotes are processed in a separate environment and diverted for later printing in the space immediately prior to the bottom margin. There is provision for the case where the last collected footnote doesn't completely fit in the available space.
&de hd \"header
& ---
&nr x 0 1 \"init footnote count
&nr y 0-\\nb \"current footer place
&ch fo -\\nbu \"reset footer trap
&if \\n(dn .fz \"leftover footnote
&de fo \"footer
&nr dn 0 \"zero last diversion size
&if \\nx \{\
&ev 1 \"expand footnotes in ev1
&nf \"retain vertical size
&FN \"footnotes
&rm FN \"delete it
&if "\\n(.z"fy" .di \"end overflow diversion
&nr x 0 \"disable fx
&ev \} \"pop environment
& ---
&de fx \"process footnote overflow
&if \\nx .di fy \"divert overflow
&de fn \"start footnote
&da FN \"divert (append) footnote
&ev 1 \"in environment 1
&if \\n+x=1 .fs \"if first, include separator
&fi \"fill mode
&de ef \"end footnote
&br \"finish output
&nr z \\n(.v \"save spacing
&ev \"pop ev
&di \"end diversion
&nr y -\\n(dn \"new footer position,
&if \\nx=1 .nr y -(\\n(.v-\\nz) \
\"uncertainty correction
&ch fo \\nyu \"y is negative
&if (\\n(nl+1v)>(\\n(.p+\\ny) \
&ch fo \\n(nlu+1v \"it didn't fit
&de fs \"separator
\l'1i' \"1 inch rule
&de fz \"get leftover footnote
&nf \"retain vertical size
&fy \"where fx put it
&nr b 1.0i \"bottom margin size
&wh 0 hd \"header trap
&wh 12i fo \"footer trap, temp position
&wh -\\nbu fx \"fx at footer position
&ch fo -\\nbu \"conceal fx with fo

The header hd initializes a footnote count register x, and sets both the current footer trap position register y and the footer trap itself to a nominal position specified in register b. In addition, if the register dn indicates a leftover footnote, fz is invoked to reprocess it. The footnote start macro fn begins a diversion (append) in environment 1, and increments the count x; if the count is one, the footnote separator fs is interpolated. The separator is kept in a separate macro to permit user redefinition. The footnote end macro ef restores the previous environment and ends the diversion after saving the spacing size in register z. y is then decremented by the size of the footnote, available in dn; then on the first footnote, y is further decremented by the difference in vertical base-line spacings of the two environments, to prevent the late triggering the footer trap from causing the last line of the combined footnotes to overflow. The footer trap is then set to the lower (on the page) of y or the current page position (nl) plus one line, to allow for printing the reference line. If indicated by x, the footer fo rereads the footnotes from FN in nofill mode in environment 1, and deletes FN. If the footnotes were too large to fit, the macro fx will be trap-invoked to redivert the overflow into fy, and the register dn will later indicate to the header whether fy is empty. Both fo and fx are planted in the nominal footer trap position in an order that causes fx to be concealed unless the fo trap is moved. The footer then terminates the overflow diversion, if necessary, and zeros x to disable fx, because the uncertainty correction together with a not-too-late triggering of the footer can result in the footnote rereading finishing before reaching the fx trap.
A good exercise for the student is to combine the multiple-column and footnote mechanisms.
T6. The Last Page
After the last input file has ended, NROFF and TROFF invoke the end macro (§7), if any, and when it finishes, eject the remainder of the page. During the eject, any traps encountered are processed normally. At the end of this last page, processing terminates unless a partial line, word, or partial word remains. If it is desired that another page be started, the end-macro
&de en \"end-macro
&em en

will deposit a null partial word, and effect another last page.

Table I

Font Style Examples

The following fonts are printed in 12-point, with a vertical spacing of 14-point, and with non-alphanumeric characters separated by ¼em space. The Special Mathematical Font was specially prepared for Bell Laboratories by Graphic Systems, Inc. of Hudson, New Hampshire. The Times Roman, Italic, and Bold are among the many standard fonts available from that company. Times Roman abcdefghijklmnopqrstuvwxyz
! $ % & ( ) ` ' * + - . , / : ; = ? [ ] |
+ o -- ­ _ ¼ ½ ¾ fi fl ff ffi ffl ° ** ' ¢ ® ©

Times Italic abcdefghijklmnopqrstuvwxyz
! $ % & ( ) ` ' * + - . , / : ; = ? [ ] |
+ o -- ­ _ ¼ ½ ¾ fi fl ff ffi ffl ° ** ' ¢ ® ©

Times Bold abcdefghijklmnopqrstuvwxyz
! $ % & ( ) ` ' * + - . , / : ; = ? [ ] |
+ o -- ­ _ ¼ ½ ¾ fi fl ff ffi ffl ° ** ' ¢ ® ©

Special Mathematical Font " ' \ ^ _ ` ~ / < > { } # @ + - = *
[alpha] [beta] [gamma] [delta] [epsilon] [zeta] [eta] [theta] [iota] [kappa] [lambda] µ [nu] [xi] [omicron] [pi] [rho] [sigma] [sigma] [tau] [upsilon] [phi] [chi] [psi] [omega]
[Gamma] [Delta] [Theta] [Lambda] [Xi] [Pi] [Sigma] [Upsilon] [Phi] [Psi] [Omega]
\(sr \(rn >= <= == ~ ~ \(!= -> <- \(ua \(da × ÷ ± \(cu \(ca \(sb \(sp \(ib \(ip \(if \(pd
§ \(gr ¬ \(is \(pt Ø \(mo *** => <= \(bs | O \(lt \(lb \(rt \(rb \(lk \(rk | \(lf \(rf \(lc \(rc |

Table II

Input Naming Conventions for ', `,and - and for Non-ASCII Special Characters

Non-ASCII characters and minus on the standard fonts.

' ' close quote ` ` open quote -- \(em 3/4 Em dash - - hyphen or ­ \(hy hyphen - \- current font minus + \(bu bullet o \(sq square _ \(ru rule ¼ \(14 1/4 ½ \(12 1/2 ¾ \(34 3/4 fi \(fi fi fl \(fl fl ff \(ff ff ffi \(Fi ffi ffl \(Fl ffl ° \(de degree ** \(dg dagger ' \(fm foot mark ¢ \(ct cent sign ® \(rg registered © \(co copyright Input Character Input Character
Char Name Name Char Name Name
' ' close quote
` ` open quote
-- \(em 3/4 Em dash
- - hyphen or
­ \(hy hyphen
- \- current font minus
+ \(bu bullet
o \(sq square
_ \(ru rule
¼ \(14 1/4
½ \(12 1/2
¾ \(34 3/4
fi \(fi fi
fl \(fl fl
ff \(ff ff
ffi \(Fi ffi
ffl \(Fl ffl
° \(de degree
** \(dg dagger
' \(fm foot mark
¢ \(ct cent sign
® \(rg registered
© \(co copyright
Non-ASCII characters and ', `, _, +, -, =, and * on the special font. The ASCII characters @, #, ", ', `, <, >, \, {, }, ~, ^, and _ exist only on the special font and are printed as a 1-em space if that font is not mounted. The following characters exist only on the special font except for the upper case Greek letter names followed by ** which are mapped into upper case English letters in whatever font is mounted on font position one (default Times Roman). The special math plus, minus, and equals are provided to insulate the appearance of equations from the choice of standard fonts.
Input Character Input Character
Char Name Name Char Name Name
+ \(pl math plus
- \(mi math minus
= \(eq math equals
* \(** math star
§ \(sc section
' \(aa acute accent
` \(ga grave accent
_ \(ul underrule
/ \(sl slash (matching backslash)
[alpha] \(*a alpha
[beta] \(*b beta
[gamma] \(*g gamma
[delta] \(*d delta
[epsilon] \(*e epsilon
[zeta] \(*z zeta
[eta] \(*y eta
[theta] \(*h theta
[iota] \(*i iota
[kappa] \(*k kappa
[lambda] \(*l lambda
µ \(*m mu
[nu] \(*n nu
[xi] \(*c xi
[omicron] \(*o omicron
[pi] \(*p pi
[rho] \(*r rho
[sigma] \(*s sigma
[sigma] \(ts terminal sigma
[tau] \(*t tau
[upsilon] \(*u upsilon
[phi] \(*f phi
[chi] \(*x chi
[psi] \(*q psi
[omega] \(*w omega
A \(*A Alpha**
B \(*B Beta**
[Gamma] \(*G Gamma
[Delta] \(*D Delta
E \(*E Epsilon**
Z \(*Z Zeta**
H \(*Y Eta**
[Theta] \(*H Theta
I \(*I Iota**
K \(*K Kappa**
[Lambda] \(*L Lambda
M \(*M Mu**
N \(*N Nu**
[Xi] \(*C Xi
O \(*O Omicron**
[Pi] \(*P Pi
P \(*R Rho**
[Sigma] \(*S Sigma
T \(*T Tau**
[Upsilon] \(*U Upsilon
[Phi] \(*F Phi
X \(*X Chi**
[Psi] \(*Q Psi
[Omega] \(*W Omega
\(sr \(sr square root
\(rn \(rn root en extender
>= \(>= >=
<= \(<= <=
== \(== identically equal
~ \(~= approx =
~ \(ap approximates
\(!= \(!= not equal
-> \(-> right arrow
<- \(<- left arrow
\(ua \(ua up arrow
\(da \(da down arrow
× \(mu multiply
÷ \(di divide
± \(+- plus-minus
\(cu \(cu cup (union)
\(ca \(ca cap (intersection)
\(sb \(sb subset of
\(sp \(sp superset of
\(ib \(ib improper subset
\(ip \(ip improper superset
\(if \(if infinity
\(pd \(pd partial derivative
\(gr \(gr gradient
¬ \(no not
\(is \(is integral sign
\(pt \(pt proportional to
Ø \(es empty set
\(mo \(mo member of
| \(br box vertical rule
*** \(dd double dagger
=> \(rh right hand
<= \(lh left hand
\(bs \(bs Bell System logo
| \(or or
O \(ci circle
\(lt \(lt left top of big curly bracket
\(lb \(lb left bottom
\(rt \(rt right top
\(rb \(rb right bot
\(lk \(lk left center of big curly bracket
\(rk \(rk right center of big curly bracket
| \(bv bold vertical
\(lf \(lf left floor (left bottom of big
square bracket)
\(rf \(rf right floor (right bottom)
\(lc \(lc left ceiling (left top)
\(rc \(rc right ceiling (right top)
troff $* m.mac m0
tbl m0a | troff $* m.mac -
tbl m[1234] | troff $* m.mac -
troff $* m.mac m5
troff $* m.mac table1
troff $* m.mac table2
troff $* m.mac add