| blob | 9446dab46a254542f3c9633fe08f606dd870d5dc |
1 '\" t
2 .ig
3 groff.man
5 Last update: 15 Apr 2002
7 This file is part of groff, the GNU roff type-setting system.
9 Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
10 written by Bernd Warken <bwarken@mayn.de>
11 maintained by Werner Lemberg <wl@gnu.org>
13 Permission is granted to copy, distribute and/or modify this document
14 under the terms of the GNU Free Documentation License, Version 1.1 or
15 any later version published by the Free Software Foundation; with the
16 Invariant Sections being this .ig-section and AUTHORS, with no
17 Front-Cover Texts, and with no Back-Cover Texts.
19 A copy of the Free Documentation License is included as a file called
20 FDL in the main directory of the groff source package.
21 ..
22 .
23 .\" --------------------------------------------------------------------
24 .\" Setup
25 .\" --------------------------------------------------------------------
26 .
27 .mso www.tmac
28 .
29 .if n \{\
30 . mso tty-char.tmac
31 . ftr CR R
32 . ftr CI I
33 . ftr CB B
34 .\}
35 .
36 .if '\*[.T]'dvi' \{\
37 . ftr CB CW
38 .\}
39 .
40 .
41 .\" --------------------------------------------------------------------
42 .\" start of macro definitions
43 .eo
44 .
45 .de c
46 ..
47 .
48 .de TPx
49 . TP 10n
50 ..
51 .c ---------------------------------------------------------------------
52 .c .Text anything ...
53 .c
54 .c All arguments are printed as text.
55 .c
56 .de Text
57 . nop \)\$*
58 ..
59 .c ---------------------------------------------------------------------
60 .c .ExecFF macro font1 font2 text1 text2 text1 text2 ...
61 .c
62 .c Concat text arguments using alternating fonts and feed into macro.
63 .c For a trailing punctuation, terminate the call with \c.
64 .c
65 .de ExecFF
66 . if (\n[.$] < 4) \
67 . return
68 . ds @a\"
69 . ds @m \$1\"
70 . ds @f1 \$2\"
71 . ds @f2 \$3\"
72 . shift 3
73 . ds @s\"
74 . while 1 \{\
75 . if (\n[.$] = 0) \
76 . break
77 . ds @a \$1\"
78 . as @s \f[\*[@f1]]\*[@a]\f[]\"
79 . shift
80 . if (\n[.$] = 0) \
81 . break
82 . ds @a \$1\"
83 . as @s \f[\*[@f2]]\*[@a]\f[]\"
84 . shift
85 . \}
86 . \*[@m] \*[@s]\f[R]
87 . ft P \" to make \c happy
88 . rm @m
89 . rm @s
90 . rm @a
91 . rm @f1
92 . rm @f2
93 ..
94 .
95 .c --------- command line option ---------
96 .
97 .de option
98 . Text \f[CB]\$*
99 . ft P
100 ..
101 .
102 .c --------- characters ---------
103 .
104 .de character
105 . ExecFF Text CB R \$*
106 ..
107 .de squoted_char
108 . ds @1 \$1\"
109 . shift
110 . ExecFF Text R CB \[oq] \*[@1] "\[cq]\$*"
111 . rm @1
112 ..
113 .de dquoted_char
114 . ds @1 \$1\"
115 . shift
116 . ExecFF Text R CB \[lq] \*[@1] "\[rq]\$*"
117 . rm @1
118 ..
119 .c --------- requests ---------
120 .
121 .c synopsis of a request
122 .de REQ
123 . if (\n[.$] = 0) \
124 . return
125 . ds @1 \$1\"
126 . shift 1
127 . ie (\n[.$] = 0) \{\
128 . TP 10n
129 . Text \f[CB]\*[@1]\f[]
130 . \}
131 . el \{\
132 . TP 10n
133 . Text \f[CB]\*[@1]\~\f[]\f[I]\$*\f[]
134 . \}
135 . rm @1
136 ..
137 .c reference of a request
138 .de request
139 . BR \$*
140 ..
141 .
142 .c --------- numerical elements ---------
143 .
144 .c number with a trailing unit
145 .de scalednumber
146 . Text \$1\^\f[CB]\$2\f[]\$3\f[R]
147 . ft P
148 ..
149 .
150 .c representation of units within the text
151 .de scaleindicator
152 . Text \f[CB]\$1\f[]\$2\f[R]
153 . ft P
154 ..
155 .
156 .c representation of mathematical operators within the text
157 .de operator
158 . squoted_char \$@
159 ..
160 .
161 .
162 .c --------- escape sequences ---------
163 .
164 .c ---------------------------------------------------------------------
165 .c .ESC name [arg]
166 .c
167 .c Synopsis of an escape sequence, optionally with argument
168 .c Args : 1 or 2; `name' obligatory, `arg' optional
169 .c name : suitable name for an escape sequence (c, (xy, [long])
170 .c arg : arbitrary word
171 .c Result : prints \namearg, where `name' is in CB, `arg' in I
172 .c
173 .de ESC
174 . if (\n[.$] < 1)
175 . ab .ESC needs 1 or 2 arguments.
176 . ExecFF IP CB I "\[rs]\$1" "\,\$2\/"
177 ..
178 .c ---------------------------------------------------------------------
179 .c .ESC[] name arg
180 .c
181 .c Synopsis for escape sequence with a bracketed long argument
182 .c Args : 2 obligatory
183 .c name : suitable name for an escape sequence (c, (xy, [long])
184 .c arg : arbitrary text
185 .c Result : prints \name[arg], where `name' is in CB, `arg' in I
186 .c
187 .de ESC[]
188 . if !(\n[.$] = 2) \
189 . ab .ESC[] needs exactly 2 arguments.
190 . ExecFF IP CB I "\[rs]\$1\[lB]" "\h'-0.2m'\$2\h'-0.15m'" \[rB]
191 ..
192 .c ---------------------------------------------------------------------
193 .c .ESCq name arg
194 .c
195 .c Synopsis for escape sequence with a bracketed long argument
196 .c Args : 2 obligatory
197 .c name : suitable name for an escape sequence (c, (xy, [long])
198 .c arg : arbitrary text
199 .c Result : prints \name'arg', where `name' is in CB, `arg' in I
200 .c
201 .de ESCq
202 . if !(\n[.$] = 2) \
203 . ab .ESCq needs exactly 2 argument.
204 . ExecFF IP CB I "\[rs]\$1\[cq]" "\h'-0.3m'\$2" \[cq]
205 ..
206 .c ---------------------------------------------------------------------
207 .c .ESC? arg
208 .c
209 .c Synopsis for escape sequence with a bracketed long argument
210 .c Args : 1 obligatory
211 .c arg : arbitrary text
212 .c Result : prints `\?arg?', where the `?' are in CB, `arg' in I
213 .c
214 .de ESC?
215 . if !(\n[.$] = 1) \
216 . ab .ESC? needs exactly 1 arguments.
217 . ExecFF IP CB I \[rs]? "\$1" ?
218 ..
219 .c ---------------------------------------------------------------------
220 .c .esc name [punct]
221 .c
222 .c Reference of an escape sequence (no args), possibly punctuation
223 .c Args : 1 obligatory
224 .c name : suitable name for an escape sequence (c, (xy, [long])
225 .c punct : arbitrary
226 .c Result : prints \name, where `name' is in B, `punct' in R
227 .c
228 .de esc
229 . if (\n[.$] < 1) \
230 . ab .esc needs 1 or 2 arguments.
231 . BR "\[rs]\$1" \$2
232 ..
233 .c ---------------------------------------------------------------------
234 .c .escarg name arg [punct]
235 .c
236 .c Reference of an escape sequence (no args)
237 .c Args : 1 obligatory, 1 optional
238 .c name : suitable name for an escape sequence (c, (xy, [long])
239 .c arg : arbitrary word
240 .c Result : prints \namearg, where
241 .c `name' is in B, `arg' in I
242 .c
243 .de escarg
244 . if (\n[.$] < 2) \
245 . ab .esc needs 2 or 3 arguments.
246 . Text \f[B]\[rs]\$1\f[]\f[I]\$2\f[]\$3
247 ..
248 .c ---------------------------------------------------------------------
249 .c .esc[] name arg [punct]
250 .c
251 .c Reference for escape sequence with a bracketed long argument
252 .c Args : 2 obligatory
253 .c name : suitable name for an escape sequence (c, (xy, [long])
254 .c arg : arbitrary text
255 .c Result : prints \name[arg], where `name' is in CB, `arg' in CI
256 .c
257 .de esc[]
258 . if (\n[.$] < 2) \
259 . ab .esc[] needs 2 or 3 arguments.
260 . Text \f[B]\[rs]\$1\[lB]\f[]\f[I]\$2\f[]\f[B]\[rB]\f[]\$3
261 ..
262 .
263 .c ---------------------------------------------------------------------
264 .c .escq name arg
265 .c
266 .c Reference for escape sequence with a bracketed long argument
267 .c Args : 2 obligatory
268 .c name : suitable name for an escape sequence (c, (xy, [long])
269 .c arg : arbitrary text
270 .c Result : prints \name'arg', where `name' is in CB, `arg' in CI
271 .c
272 .de escq
273 . if (\n[.$] < 2) \
274 . ab .escq needs 2 arguments.
275 . Text \f[B]\[rs]\$1\[cq]\f[]\f[I]\$2\f[]\f[B]\[cq]\f[]\$3
276 ..
277 .
278 .c --------- strings ---------
279 .
280 .c synopsis for string, with \*[]
281 .de STRING
282 . ds @1 \$1\"
283 . shift 1
284 . TP 10n
285 . ExecFF Text R CB \[rs]*[ \*[@1]\f[]\f[R]] \$*
286 . rm @1
287 ..
288 .c synopsis for a long string
289 .de string
290 . if (\n[.$] = 0) \
291 . return
292 . Text \f[CB]\[rs]*\[lB]\$1\[rB]\f[]\$2
293 ..
294 .
295 .
296 .c --------- registers ---------
297 .
298 .c synopsis for registers, with \n[]
299 .de REG
300 . ds @1 \$1\"
301 . shift 1
302 . TP 10n
303 . ExecFF Text R CB \[rs]n[ \*[@1]\f[]\f[R]] \$*
304 . rm @1
305 ..
306 .c reference of a register, without decoration
307 .de register
308 . Text register
309 . BR \$*
310 ..
311 .
312 .ec
313 .\" end of macro definitions
314 .
315 .
316 .\" --------------------------------------------------------------------
317 .\" Title
318 .\" --------------------------------------------------------------------
319 .
320 .TH GROFF @MAN7EXT@ "@MDATE@" "Groff Version @VERSION@"
321 .SH NAME
322 groff \- a short reference for the GNU roff language
323 .
324 .
325 .\" --------------------------------------------------------------------
326 .SH DESCRIPTION
327 .\" --------------------------------------------------------------------
328 .
329 The name
330 .I groff
331 stands for
332 .I GNU roff
333 and is the free implementation of the roff type-setting system.
334 .
335 See
336 .BR roff (@MAN7EXT@)
337 for a survey and the background of the groff system.
338 .
339 .P
340 This document gives only short descriptions of the predefined roff
341 language elements as used in groff.
342 .
343 Both the classical features and the groff extensions are provided.
344 .
345 .P
346 Historically, the
347 .I roff language
348 was called
349 .IR troff .
350 .I groff
351 is compatible with the classical system and provides proper
352 extensions.
353 .
354 So in GNU, the terms
355 .IR roff ,
356 .IR troff ,
357 and
358 .I groff language
359 could be used as synonyms.
360 .
361 However
362 .I troff
363 slightly tends to refer more to the classical aspects, whereas
364 .I groff
365 emphasizes the GNU extensions, and
366 .I roff
367 is the general term for the language.
368 .
369 .P
370 This file is only a short version of the complete documentation that
371 is found in the
372 .I groff
373 .BR info (1)
374 file, which contains more detailed, actual, and concise information.
375 .
376 .P
377 The general syntax for writing groff documents is relatively easy, but
378 writing extensions to the roff language can be a bit harder.
379 .
380 .P
381 The roff language is line-oriented.
382 .
383 There are only two kinds of lines, control lines and text lines.
384 .
385 The control lines start with a control character, by default a period
386 .dquoted_char .
387 or a single quote
388 .dquoted_char ' ;
389 all other lines are text lines.
390 .
391 .P
392 .B Control lines
393 represent commands, optionally with arguments.
394 .
395 They have the following syntax.
396 .
397 The leading control character can be followed by a command name;
398 arguments, if any, are separated by blanks from the command name and
399 among themselves, for example,
400 .RS
401 .
402 .P
403 .Text .command_name arg1 arg2
404 .RE
405 .
406 .P
407 For indentation, any number of space or tab characters can be inserted
408 between the leading control character and the command name, but the
409 control character must be on the first position of the line.
410 .
411 .P
412 .B Text lines
413 represent the parts that will be printed.
414 They can be modified by escape sequences, which are recognized by a
415 leading backslash
416 .squoted_char \[rs] .
417 These are in-line or even in-word formatting elements or functions.
418 .
419 Some of these take arguments separated by single quotes
420 .dquoted_char ' ,
421 others are regulated by a length encoding introduced by an open
422 parenthesis
423 .squoted_char (
424 or enclosed in brackets
425 .squoted_char [
426 and
427 .squoted_char ] .
428 .
429 .P
430 The roff language provides flexible instruments for writing language
431 extension, such as macros.
432 .
433 When interpreting macro definitions, the roff system enters a special
434 operating mode, called the
435 .BR "copy mode" .
436 .
437 .P
438 The copy mode behavior can be quite tricky, but there are some rules
439 that ensure a safe usage.
440 .
441 .IP 1.
442 Printable backslashes must be denoted as
443 .esc e .
444 To be more precise,
445 .esc e
446 represents the current escape character.
447 .
448 To get a backslash glyph, use
449 .esc (rs
450 or
451 .esc [rs] .
452 .IP 2.
453 Double all backslashes.
454 .IP 3.
455 Begin all text lines with the special non-spacing character
456 .esc & .
457 .
458 .P
459 This does not produce the most efficient code, but it should work as a
460 first measure.
461 .
462 For better strategies, see the groff info file and
463 .BR groff_tmac (@MAN5EXT@).
464 .
465 .P
466 Reading roff source files is easier, just reduce all double backslashes
467 to a single one in all macro definitions.
468 .
469 .
470 .\" --------------------------------------------------------------------
471 .SH "GROFF ELEMENTS"
472 .\" --------------------------------------------------------------------
473 .
474 The roff language elements add formatting information to a text file.
475 .
476 The fundamental elements are predefined commands and variables that
477 make roff a full-blown programming language.
478 .
479 .P
480 There are two kinds of roff commands, possibly with arguments.
481 .B Requests
482 are written on a line of their own starting with a dot
483 .squoted_char .
484 or a
485 .dquoted_char ' ,
486 whereas
487 .B Escape sequences
488 are in-line functions and in-word formatting elements starting with a
489 backslash
490 .squoted_char \[rs] .
491 .
492 .P
493 The user can define her own formatting commands using the
494 .request de
495 request.
496 .
497 These commands are called
498 .BR macros ,
499 but they are used exactly like requests.
500 .
501 Macro packages are pre-defined sets of macros written in the groff
502 language.
503 .
504 A user's possibilities to create escape sequences herself is very
505 limited, only special characters can be mapped.
506 .
507 .P
508 The groff language provides several kinds of variables with
509 different interfaces.
510 .
511 There are pre-defined variables, but the user can define her own
512 variables as well.
513 .
514 .P
515 .B String
516 variables store character sequences.
517 .
518 They are set with the
519 .request ds
520 request and retrieved by the
521 .esc *
522 escape sequences.
523 .
524 .P
525 .B Register
526 variables can store numerical values, numbers with a scale unit, and
527 occasionally string-like objects.
528 .
529 They are set with the
530 .request nr
531 request and retrieved by the
532 .esc n
533 escape sequences.
534 .
535 .P
536 .B Environments
537 allow the user to temporarily store global formatting parameters like
538 line length, font size, etc.\& for later reuse.
539 .
540 This is done by the
541 .request ev
542 request.
543 .
544 .P
545 .B Fonts
546 are identified either by a name or by an internal number.
547 .
548 The current font is chosen by the
549 .request ft
550 request or by the
551 .esc f
552 escape sequences.
553 .
554 Each device has special fonts, but the following fonts are available
555 for all devices.
556 .B R
557 is the standard font Roman.
558 .B B
559 is its
560 .B bold
561 counterpart.
562 .
563 The
564 .I italic
565 font is called
566 .B I
567 is everywhere available, but on text devices, it is displayed as an
568 underlined Roman font.
569 .
570 For the graphical output devices, there exist constant-width pendants
571 of these fonts,
572 .BR CR ,
573 .BR CI ,
574 and
575 .BR CB .
576 On text devices, all characters have a constant width anyway.
577 .
578 .P
579 Moreover, there are some advanced roff elements.
580 .
581 A
582 .B diversion
583 stores information into a macro for later usage.
584 .
585 A
586 .B trap
587 is a positional condition like a certain number of lines from page top
588 or in a diversion or in the input.
589 .
590 Some action can be prescribed to be run automatically when the
591 condition is met.
592 .
593 .P
594 More detailed information and examples can be found in the groff info
595 file.
596 .
597 .
598 .\" --------------------------------------------------------------------
599 .SH "CONTROL CHARACTERS"
600 .\" --------------------------------------------------------------------
601 .
602 There is a small set of characters that have a special controlling
603 task in certain conditions.
604 .
605 .TP
606 .character .
607 A dot is only special at the beginning of a line or after the
608 condition in the requests
609 .request if ,
610 .request ie ,
611 .request el ,
612 and
613 .request while .
614 There it is the control character that introduces a request (or macro).
615 .
616 The special behavior can be delayed by using the
617 .esc .
618 escape.
619 .
620 By using the
621 .request cc
622 request, the control character can be set to a different character,
623 making the dot
624 .squoted_char .
625 a non-special character.
626 .IP ""
627 In all other positions, it just means a dot character.
628 .
629 In text paragraphs, it is advantageous to start each sentence at a
630 line of its own.
631 .
632 .TP
633 .character '
634 The single quote has two controlling tasks.
635 .
636 At the beginning of a line and in the conditional requests it is the
637 non-breaking control character.
638 .
639 That means that it introduces a request like the dot, but with the
640 additional property that this request doesn't cause a linebreak.
641 .
642 By using the
643 .request c2
644 request, the non-break control character can be set to a different
645 character.
646 .
647 .IP ""
648 As a second task, it is the most commonly used argument separator in
649 some functional escape sequences (but any pair of characters not part
650 of the argument will work).
651 .
652 In all other positions, it denotes the single quote or apostrophe
653 character.
654 .
655 Groff provides a printable representation with the
656 .esc (cq
657 escape sequence.
658 .
659 .TP
660 .character \[dq]
661 The double quote is used to enclose arguments in requests and macros.
662 In the
663 .request ds
664 and
665 .request as
666 requests, a leading double quote in the argument will be stripped off,
667 making everything else afterwards the string to be defined (enabling
668 leading whitespace).
669 .
670 The escaped double quote
671 .esc \[dq]
672 introduces a comment.
673 .
674 Otherwise, it is not special.
675 .
676 Groff provides a printable representation with the
677 .esc (dq
678 escape sequence.
679 .
680 .TP
681 .character \[rs]
682 The backslash usually introduces an escape sequence (this can be
683 changed with the
684 .request ec
685 request).
686 .
687 A printed version of the escape character is the
688 .esc e
689 escape; a backslash glyph can be obtained by
690 .esc (rs .
691 .TP
692 .character (
693 The open parenthesis is only special in escape sequences when
694 introducing an escape name or argument consisting of exactly two
695 characters.
696 .
697 In groff, this behavior can be replaced by the \f[CB][]\f[] construct.
698 .TP
699 .character [
700 The opening bracket is only special in groff escape sequences; there
701 it is used to introduce a long escape name or long escape argument.
702 .
703 Otherwise, it is non-special, e.g.\& in macro calls.
704 .TP
705 .character ]
706 The closing bracket is only special in groff escape sequences; there
707 it terminates a long escape name or long escape argument.
708 .
709 Otherwise, it is non-special.
710 .TP
711 \f[CI]space\f[]
712 Space characters are only functional characters.
713 .
714 They separate the arguments in requests or macros, and the words in
715 text lines.
716 .
717 They are subject to groff's horizontal spacing calculations.
718 .
719 To get a defined space width, escape sequences like
720 .squoted_char "\[rs]\ "
721 (this is the escape character followed by a space),
722 .esc | ,
723 .esc ^ ,
724 or
725 .esc h
726 should be used.
727 .
728 .IP \f[CI]newline\f[]
729 In text paragraphs, newlines mostly behave like space characters.
730 .
731 Continuation lines can be specified by an escaped newline, i.e., by
732 specifying a backslash
733 .squoted_char \[rs]
734 as the last character of a line.
735 .IP \f[CI]tab\f[]
736 If a tab character occurs during text the interpreter makes a
737 horizontal jump to the next pre-defined tab position.
738 .
739 There is a sophisticated interface for handling tab positions.
740 .
741 .
742 .\" --------------------------------------------------------------------
743 .SH "NUMERICAL EXPRESSIONS"
744 .\" --------------------------------------------------------------------
745 .
746 A
747 .B numerical value
748 is a signed or unsigned integer or float with or without an appended
749 scale indicator.
750 .
751 A
752 .B scale indicator
753 is a one-character abbreviation for a unit of measurement.
754 .
755 A number followed by a scale indicator signifies a size value.
756 .
757 By default, numerical values do not have a scale indicator, i.e., they
758 are normal numbers.
759 .
760 .P
761 The
762 .I roff
763 language defines the following scale indicators.
764 .
765 .
766 .P
767 .PD 0
768 .RS
769 .
770 .TPx
771 .B c
772 Centimeter
773 .
774 .TPx
775 .B i
776 Inch
777 .
778 .TPx
779 .B P
780 Pica\ \[eq]\ 1/6\ inch
781 .
782 .TPx
783 .B p
784 Point\ \[eq]\ 1/72\ inch
785 .
786 .TPx
787 .B m
788 Em\ \[eq]\ \f[R]the font size in points (width of letter `\f[CR]m\f[R]')
789 .
790 .TPx
791 .B M
792 100\^th \f[R]of an \f[CR]Em
793 .
794 .TPx
795 .B n
796 En\ \[eq]\ Em/2
797 .
798 .TPx
799 .B u
800 Basic unit for actual output device
801 .
802 .TPx
803 .B v
804 Vertical line space in basic units
805 scaled point\ \[eq]\ 1/\f[CI]sizescale\f[R] of a point (defined in
806 font \f[I]DESC\f[] file)
807 .
808 .TPx
809 .B f
810 Scale by 65536.
811 .RE
812 .PD
813 .
814 .P
815 .B Numerical expressions
816 are combinations of the numerical values defined above with the
817 following arithmetical operators already defined in classical troff.
818 .
819 .P
820 .PD 0
821 .RS
822 .
823 .TPx
824 .B +
825 Addition
826 .
827 .TPx
828 .B \-
829 Subtraction
830 .
831 .TPx
832 .B *
833 Multiplication
834 .
835 .TPx
836 .B /
837 Division
838 .
839 .TPx
840 .B %
841 Modulo
842 .
843 .TPx
844 .B =
845 Equals
846 .
847 .TPx
848 .B ==
849 Equals
850 .
851 .TPx
852 .B <
853 Less than
854 .
855 .TPx
856 .B >
857 Greater than
858 .
859 .TPx
860 .B <=
861 Less or equal
862 .
863 .TPx
864 .B >=
865 Greater or equal
866 .
867 .TPx
868 .B &
869 Logical and
870 .
871 .TPx
872 .B :
873 Logical or
874 .
875 .TPx
876 .B !
877 Logical not
878 .
879 .TPx
880 .B (
881 Grouping of expressions
882 .
883 .TPx
884 .B )
885 Close current grouping
886 .
887 .RE
888 .PD
889 .
890 .P
891 Moreover,
892 .I groff
893 added the following operators for numerical expressions:
894 .
895 .P
896 .PD 0
897 .RS
898 .
899 .TPx
900 .ExecFF Text I CB e1 >? e2
901 The maximum of
902 .I e1
903 and
904 .IR e2 .
905 .
906 .TPx
907 .ExecFF Text I CB e1 <? e2
908 The minimum of
909 .I e1
910 and
911 .IR e2 .
912 .
913 .TPx
914 .ExecFF Text CB I ( c ; e )
915 Evaluate
916 .I e
917 using
918 .I c
919 as the default scaling indicator.
920 .
921 .RE
922 .PD
923 .
924 .P
925 For details see the groff info file.
926 .
927 .
928 .\" --------------------------------------------------------------------
929 .SH CONDITIONS
930 .\" --------------------------------------------------------------------
931 .
932 .B Conditions
933 occur in tests raised by the
934 .request if ,
935 .request ie ,
936 and the
937 .request while
938 requests.
939 .
940 The following table characterizes the different types of conditions.
941 .
942 .P
943 .PD 0
944 .RS
945 .
946 .TPx
947 .I N
948 A numerical expression
949 .I N
950 yields true if its value is greater than\~0.
951 .
952 .TPx
953 .BI ! N
954 True if the value of
955 .I I
956 is\~0.
957 .
958 .TPx
959 .BI ' s1 ' s2 '
960 True if string\~\c
961 .I s1
962 is identical to string\~\c
963 .IR s2 .
964 .
965 .TPx
966 .BI !' s1 ' s2 '
967 True if string\~\c
968 .I s1
969 is not identical to string\~\c
970 .IR s2 .
971 .
972 .TPx
973 .BI c ch
974 True if there is a character\~\c
975 .I ch
976 available.
977 .
978 .TPx
979 .BI d name
980 True if there is a string, macro, diversion, or request called
981 .IR name .
982 .
983 .TPx
984 .B e
985 Current page number is even.
986 .
987 .TPx
988 .B o
989 Current page number is odd.
990 .
991 .TPx
992 .BI m name
993 True if there is a color called
994 .IR name .
995 .
996 .TPx
997 .B n
998 Formatter is
999 .BR nroff .
1000 .
1001 .TPx
1002 .BI r reg
1003 True if there is a register named
1004 .IR reg .
1005 .
1006 .TPx
1007 .B t
1008 Formatter is
1009 .BR troff .
1010 .
1011 .RE
1012 .PD
1013 .
1014 .
1015 .\" --------------------------------------------------------------------
1016 .SH REQUESTS
1017 .\" --------------------------------------------------------------------
1018 .
1019 This section provides a short reference for the predefined requests.
1020 .
1021 In groff, request and macro names can be arbitrarily long.
1022 .
1023 No bracketing or marking of long names is needed.
1024 .
1025 .P
1026 Most requests take one or more arguments.
1027 .
1028 The arguments are separated by space characters (no tabs!); there is
1029 no inherent limit for their length or number.
1030 .
1031 An argument can be enclosed by a pair of double quotes.
1032 .
1033 This is very handy if an argument contains space characters, e.g.,
1034 .RI \[dq] "arg with space" \[dq]
1035 denotes a single argument.
1036 .
1037 .P
1038 Some requests have optional arguments with a different behaviour.
1039 .
1040 Not all of these details are outlined here.
1041 .
1042 Refer to the groff info file and
1043 .BR groff_diff (@MAN7EXT@)
1044 for all details.
1045 .
1046 .P
1047 In the following request specifications, most argument names were
1048 chosen to be descriptive.
1049 .
1050 Only the following denotations need clarification.
1051 .
1052 .P
1053 .PD 0
1054 .RS
1055 .
1056 .TPx
1057 .I c
1058 denotes a single character.
1059 .
1060 .TPx
1061 .I font
1062 a font either specified as a font name or a font number.
1063 .
1064 .TPx
1065 .I anything
1066 all characters up to the end of the line or within
1067 .esc {
1068 and
1069 .esc } .
1070 .
1071 .TPx
1072 .I n
1073 is a numerical expression that evaluates to an integer value.
1074 .
1075 .TPx
1076 .I N
1077 is an arbitrary numerical expression, signed or unsigned.
1078 .
1079 .TPx
1080 .I \[+-]N
1081 has three meanings depending on its sign, described below.
1082 .
1083 .RE
1084 .PD
1085 .
1086 .P
1087 If an expression defined as
1088 .I \[+-]N
1089 starts with a
1090 .squoted_char +
1091 sign the resulting value of the expression will be added to an already
1092 existing value inherent to the related request, e.g.\& adding to a number
1093 register.
1094 .
1095 If the expression starts with a
1096 .squoted_char -
1097 the value of the expression will be subtracted from the request value.
1098 .
1099 .P
1100 Without a sign,
1101 .I N
1102 replaces the existing value directly.
1103 .
1104 To assign a negative number either prepend\~0 or enclose the negative
1105 number in parentheses.
1106 .
1107 .
1108 .\" --------------------------------------------------------------------
1109 .SS "Request Short Reference"
1110 .\" --------------------------------------------------------------------
1111 .
1112 .PD 0
1113 .
1114 .REQ .
1115 Empty line, ignored.
1116 .
1117 Useful for structuring documents.
1118 .
1119 .REQ .\[rs]\[dq] anything
1120 Complete line is a comment.
1121 .
1122 .REQ .ab string
1123 Print
1124 .I string
1125 on standard error, exit program.
1126 .
1127 .REQ .ad
1128 Begin line adjustment for output lines in current adjust mode.
1129 .
1130 .REQ .ad c
1131 Start line adjustment in mode
1132 .I c
1133 (\f[CI]c\f[]\f[CR]\|\^\[eq]\|l,r,b,n\f[]).
1134 .
1135 .REQ .af register c
1136 Assign format
1137 .I c
1138 to
1139 .I register
1140 (\f[CI]c\f[]\f[CR]\|\^\[eq]\|l,i,I,a,A\f[]).
1141 .
1142 .REQ .aln alias register
1143 Create alias name for
1144 .IR register .
1145 .
1146 .REQ .als alias object
1147 Create alias name for request, string, macro, or diversion
1148 .IR object .
1149 .
1150 .REQ .am macro
1151 Append to
1152 .I macro
1153 until
1154 .B ..\&
1155 is encountered.
1156 .
1157 .REQ .am macro end
1158 Append to
1159 .I macro
1160 until
1161 .request .end
1162 is called.
1163 .
1164 .REQ .ami macro
1165 Append to a macro whose name is contained in the string register
1166 .I macro
1167 until
1168 .B ..\&
1169 is encountered.
1170 .
1171 .REQ .ami macro end
1172 Append to a macro indirectly.
1173 .I macro
1174 and
1175 .I end
1176 are string registers whose contents are interpolated for the macro name
1177 and the end macro, respectively.
1178 .
1179 .REQ .am1 macro
1180 Same as
1181 .request .am
1182 but with compatibility mode switched off during macro expansion.
1183 .
1184 .REQ .am1 macro end
1185 Same as
1186 .request .am
1187 but with compatibility mode switched off during macro expansion.
1188 .
1189 .REQ .as stringvar anything
1190 Append
1191 .I anything
1192 to
1193 .IR stringvar .
1194 .
1195 .REQ .asciify diversion
1196 Unformat ASCII characters, spaces, and some escape sequences in
1197 .IR diversion .
1198 .
1199 .REQ .as1 stringvar anything
1200 Same as
1201 .request .as
1202 but with compatibility mode switched off during string expansion.
1203 .
1204 .REQ .backtrace
1205 Print a backtrace of the input on stderr.
1206 .
1207 .REQ .bd font N
1208 Embolden
1209 .I font
1210 by
1211 .IR N -1
1212 units.
1213 .
1214 .REQ .bd S font N
1215 Embolden Special Font
1216 .I S
1217 when current font is
1218 .IR font .
1219 .
1220 .REQ .blm
1221 Unset the blank line macro.
1222 .
1223 .REQ .blm macro
1224 Set the blank line macro to
1225 .IR macro .
1226 .
1227 .REQ .box
1228 End current diversion.
1229 .
1230 .REQ .box macro
1231 Divert to
1232 .IR macro ,
1233 omitting a partially filled line.
1234 .
1235 .REQ .boxa
1236 End current diversion.
1237 .
1238 .REQ .boxa macro
1239 Divert and append to
1240 .IR macro ,
1241 omitting a partially filled line.
1242 .
1243 .REQ .bp
1244 Eject current page and begin new page.
1245 .
1246 .REQ .bp \[+-]N
1247 Eject current page; next page number
1248 .IR \[+-]N .
1249 .
1250 .REQ .br
1251 Line break.
1252 .
1253 .REQ .brp
1254 Break and spread output line.
1255 Same as
1256 .esc p .
1257 .
1258 .REQ .break
1259 Break out of a while loop.
1260 .
1261 .REQ .c2
1262 Reset no-break control character to
1263 .dquoted_char ' .
1264 .
1265 .REQ .c2 c
1266 Set no-break control character to
1267 .IR c .
1268 .
1269 .REQ .cc
1270 Reset control character to
1271 .squoted_char . .
1272 .
1273 .REQ .cc c
1274 Set control character to
1275 .IR c .
1276 .
1277 .REQ .ce
1278 Center the next input line.
1279 .
1280 .REQ .ce N
1281 Center following
1282 .I N
1283 input lines.
1284 .
1285 .REQ .cf filename
1286 Copy contents of file
1287 .I filename
1288 unprocessed to stdout or to the diversion.
1289 .
1290 .REQ .cflags mode c1 c2 .\|.\|.\&
1291 Treat characters
1292 .IR c1 ,
1293 .IR c2 ,
1294 .I .\|.\|.\&
1295 according to
1296 .I mode
1297 number.
1298 .
1299 .REQ .ch trap N
1300 Change
1301 .I trap
1302 location
1303 to
1304 .I N .
1305 .
1306 .REQ .char c anything
1307 Define character
1308 .I c
1309 as string
1310 .IR anything .
1311 .
1312 .REQ .chop object
1313 Chop the last character off macro, string, or diversion
1314 .IR object .
1315 .
1316 .REQ .close stream
1317 Close the
1318 .IR stream .
1319 .
1320 .REQ .continue
1321 Finish the current iteration of a while loop.
1322 .
1323 .REQ .cp
1324 Enable compatibility mode.
1325 .
1326 .REQ .cp N
1327 If
1328 .I N
1329 is zero disable compatibility mode, otherwise enable it.
1330 .
1331 .REQ .cs font N M
1332 Set constant character width mode for
1333 .I font
1334 to
1335 .IR N /36
1336 ems with em
1337 .IR M .
1338 .
1339 .REQ .cu N
1340 Continuous underline in nroff, like
1341 .request .ul
1342 in troff.
1343 .
1344 .REQ .da
1345 End current diversion.
1346 .
1347 .REQ .da macro
1348 Divert and append to
1349 .IR macro .
1350 .
1351 .REQ .de macro
1352 Define or redefine
1353 .I macro
1354 until
1355 .B ..\&
1356 is encountered.
1357 .
1358 .REQ .de macro end
1359 Define or redefine
1360 .I macro
1361 until
1362 .request .end
1363 is called.
1364 .
1365 .REQ .de1 macro
1366 Same as
1367 .request .de
1368 but with compatibility mode switched off during macro expansion.
1369 .
1370 .REQ .de1 macro end
1371 Same as
1372 .request .de
1373 but with compatibility mode switched off during macro expansion.
1374 .
1375 .REQ .defcolor color scheme component
1376 Define or redefine a color with name
1377 .IR color .
1378 .I scheme
1379 can be
1380 .BR rgb ,
1381 .BR cym ,
1382 .BR cymk ,
1383 .BR gray ,
1384 or
1385 .BR grey .
1386 .I component
1387 can be single components specified as fractions in the range 0 to 1
1388 (default scale indicator\~\c
1389 .scaleindicator f ),
1390 as a string of two-digit hexadecimal color components with a leading
1391 .BR # ,
1392 or as a string of four-digit hexadecimal components with two leading
1393 .BR # .
1394 The color
1395 .B default
1396 can't be redefined.
1397 .
1398 .REQ .dei macro
1399 Define or redefine a macro whose name is contained in the string register
1400 .I macro
1401 until
1402 .B ..\&
1403 is encountered.
1404 .
1405 .REQ .dei macro end
1406 Define or redefine a macro indirectly.
1407 .I macro
1408 and
1409 .I end
1410 are string registers whose contents are interpolated for the macro name
1411 and the end macro, respectively.
1412 .
1413 .REQ .di
1414 End current diversion.
1415 .
1416 .REQ .di macro
1417 Divert to
1418 .I macro .
1419 .
1420 .REQ .do name
1421 Interpret
1422 .request .name
1423 with compatibility mode disabled.
1424 .
1425 .REQ .ds stringvar anything
1426 Set
1427 .I stringvar
1428 to
1429 .IR anything .
1430 .
1431 .REQ .ds1 stringvar anything
1432 Same as
1433 .request .ds
1434 but with compatibility mode switched off during string expansion.
1435 .
1436 .REQ .dt N trap
1437 Set diversion trap to position
1438 .I N
1439 (default scale indicator\~\c
1440 .scaleindicator v ).
1441 .
1442 .REQ .ec
1443 Reset escape character to
1444 .squoted_char \[rs] .
1445 .
1446 .REQ .ec c
1447 Set escape character to
1448 .IR c .
1449 .
1450 .REQ .ecr
1451 Restore escape character saved with
1452 .request .ecs .
1453 .
1454 .REQ .ecs
1455 Save current escape character.
1456 .
1457 .REQ .el anything
1458 Else part for if-else (\c
1459 .request ie )
1460 request.
1461 .
1462 .REQ .em macro
1463 The
1464 .I macro
1465 will be run after the end of input.
1466 .
1467 .REQ .eo
1468 Turn off escape character mechanism.
1469 .
1470 .REQ .ev
1471 Switch to previous environment.
1472 .
1473 .REQ .ev env
1474 Push down environment number or name
1475 .I env
1476 and switch to it.
1477 .
1478 .REQ .evc env
1479 Copy the contents of environment
1480 .I env
1481 to the current environment.
1482 No pushing or popping.
1483 .
1484 .REQ .ex
1485 Exit from roff processing.
1486 .
1487 .REQ .fam
1488 Return to previous font family.
1489 .
1490 .REQ .fam name
1491 Set the current font family to
1492 .IR name .
1493 .
1494 .REQ .fc
1495 Disable field mechanism.
1496 .
1497 .REQ .fc a
1498 Set field delimiter to
1499 .I a
1500 and pad character to space.
1501 .
1502 .REQ .fc a b
1503 Set field delimiter to
1504 .I a
1505 and pad character to
1506 .IR b .
1507 .
1508 .REQ .fchar c anything
1509 Define fallback character
1510 .I c
1511 as string
1512 .IR anything .
1513 .
1514 .REQ .fi
1515 Fill output lines.
1516 .
1517 .REQ .fl
1518 Flush output buffer.
1519 .
1520 .REQ .fp n font
1521 Mount
1522 .I font
1523 on position
1524 .IR n .
1525 .
1526 .REQ .fp n internal external
1527 Mount font with long
1528 .I external
1529 name to short
1530 .I internal
1531 name on position
1532 .IR n .
1533 .
1534 .REQ .fspecial font s1 s2 .\|.\|.\&
1535 When the current font is
1536 .IR font ,
1537 then the fonts
1538 .IR s1 ,
1539 .IR s2 ,
1540 .I .\|.\|.\&
1541 will be special.
1542 .
1543 .REQ .ft
1544 Return to previous font.
1545 Same as
1546 .request \[rs]f[]
1547 or
1548 .request \[rs]fP .
1549 .
1550 .REQ .ft font
1551 Change to font name or number
1552 .IR font ;
1553 same as
1554 .esc[] f font
1555 escape sequence.
1556 .
1557 .REQ .ftr font1 font2
1558 Translate
1559 .I font1
1560 to
1561 .IR font2 .
1562 .
1563 .REQ .hc
1564 Remove additional hyphenation indicator character.
1565 .
1566 .REQ .hc c
1567 Set up additional hyphenation indicator character\~\c
1568 .IR c .
1569 .
1570 .REQ .hcode c1 code1 c2 code2 .\|.\|.\&
1571 Set the hyphenation code of character
1572 .I c1
1573 to
1574 .IR code1 ,
1575 that of
1576 .I c2
1577 to
1578 .IR code2 ,
1579 etc.
1580 .
1581 .REQ .hla lang
1582 Set the current hyphenation language to
1583 .IR lang .
1584 .
1585 .REQ .hlm n
1586 Set the maximum number of consecutive hyphenated lines to
1587 .IR n .
1588 .
1589 .REQ .hpf file
1590 Read hyphenation patterns from
1591 .IR file .
1592 .
1593 .REQ .hpfa file
1594 Append hyphenation patterns from
1595 .IR file .
1596 .
1597 .REQ .hpfcode file
1598 Set input mapping for
1599 .request .hpf .
1600 .
1601 .REQ .hw words
1602 List of
1603 .I words
1604 with exceptional hyphenation.
1605 .
1606 .REQ .hy N
1607 Switch to hyphenation mode
1608 .IR N .
1609 .
1610 .REQ .hym n
1611 Set the hyphenation margin to
1612 .I n
1613 (default scale indicator\~\c
1614 .scaleindicator m ).
1615 .
1616 .REQ .hys n
1617 Set the hyphenation space to
1618 .IR n .
1619 .
1620 .REQ .ie cond anything
1621 If
1622 .I cond
1623 then
1624 .I anything
1625 else goto
1626 .request .el .
1627 .
1628 .REQ .if cond anything
1629 If
1630 .I cond
1631 then
1632 .IR anything ;
1633 otherwise do nothing.
1634 .
1635 .REQ .ig
1636 Ignore text until
1637 .B ..\&
1638 is encountered.
1639 .
1640 .REQ .ig end
1641 Ignore text until
1642 .request .end .
1643 .
1644 .REQ .in
1645 Change to previous indent value.
1646 .
1647 .REQ .in \[+-]N
1648 Change indent according to
1649 .I \[+-]N
1650 (default scale indicator\~\c
1651 .scaleindicator m ).
1652 .
1653 .REQ .it N trap
1654 Set an input-line count trap for the next
1655 .I N
1656 lines.
1657 .
1658 .REQ .itc N trap
1659 Same as
1660 .request .it
1661 but count lines interrupted with
1662 .esc c
1663 as one line.
1664 .
1665 .REQ .kern
1666 Enable pairwise kerning.
1667 .
1668 .REQ .kern n
1669 If
1670 .I n
1671 is zero, disable pairwise kerning, otherwise enable it.
1672 .
1673 .REQ .lc
1674 Remove leader repetition character.
1675 .
1676 .REQ .lc c
1677 Set leader repetition character to\~\c
1678 .IR c .
1679 .
1680 .REQ .length register anything
1681 Write the length of the string
1682 .I anything
1683 in
1684 .IR register .
1685 .
1686 .REQ .linetabs
1687 Enable line-tabs mode (i.e., calculate tab positions relative to output
1688 line).
1689 .
1690 .REQ .linetabs n
1691 If
1692 .I n
1693 is zero, disable line-tabs mode, otherwise enable it.
1694 .
1695 .REQ .lf N file
1696 Set input line number to
1697 .I N
1698 and filename to
1699 .IR file .
1700 .
1701 .REQ .lg N
1702 Ligature mode on if
1703 .IR N >0.
1704 .
1705 .REQ .ll
1706 Change to previous line length.
1707 .
1708 .REQ .ll \[+-]N
1709 Set line length according to
1710 .I \[+-]N
1711 (default size
1712 .scalednumber 6.5 i ,
1713 default scale indicator\~\c
1714 .scaleindicator m ).
1715 .
1716 .REQ .ls
1717 Change to the previous value of additional intra-line skip.
1718 .
1719 .REQ .ls N
1720 Set additional intra-line skip value to
1721 .IR N ,
1722 i.e.,
1723 .IR N -1
1724 blank lines are inserted after each text output line.
1725 .
1726 .REQ .lt \[+-]N
1727 Length of title (default scale indicator\~\c
1728 .scaleindicator m ).
1729 .
1730 .REQ .mc
1731 Margin character off.
1732 .
1733 .REQ .mc c
1734 Print character
1735 .I c
1736 after each text line at actual distance from right margin.
1737 .
1738 .REQ .mc c N
1739 Set margin character to
1740 .I c
1741 and distance to
1742 .I N
1743 from right margin (default scale indicator\~\c
1744 .scaleindicator m ).
1745 .
1746 .REQ .mk register
1747 Mark current vertical position in
1748 .IR register .
1749 .
1750 .REQ .mso file
1751 The same as the .so request except that
1752 .I file
1753 is searched in the tmac directories.
1754 .
1755 .REQ .na
1756 No output-line adjusting.
1757 .
1758 .REQ .ne
1759 Need a one-line vertical space.
1760 .
1761 .REQ .ne N
1762 Need
1763 .I N
1764 vertical space (default scale indicator\~\c
1765 .scaleindicator v ).
1766 .
1767 .REQ .nf
1768 No filling or adjusting of output-lines.
1769 .
1770 .REQ .nh
1771 No hyphenation.
1772 .
1773 .REQ .nm
1774 Number mode off.
1775 .
1776 .REQ .nm \[+-]N \fR[\fPM \fR[\fPS \fR[\fPI\fR]]]\fP
1777 In line number mode, set number, multiple, spacing, and indent.
1778 .
1779 .REQ .nn
1780 Do not number next line.
1781 .
1782 .REQ .nn N
1783 Do not number next
1784 .I N
1785 lines.
1786 .
1787 .REQ .nop anything
1788 Always execute
1789 .IR anything .
1790 .
1791 .REQ .nr register \[+-]N M
1792 Define or modify
1793 .I register
1794 using
1795 .I \[+-]N
1796 with auto-increment
1797 .IR M .
1798 .
1799 .REQ .nroff
1800 Make the built-in condition
1801 .B n
1802 true and
1803 .B t
1804 false.
1805 .
1806 .REQ .ns
1807 Turn no-space mode on.
1808 .
1809 .REQ .nx
1810 Immediately jump to end of current file.
1811 .
1812 .REQ .nx filename
1813 Next file.
1814 .
1815 .REQ .open stream filename
1816 Open
1817 .register filename
1818 for writing and associate the stream named
1819 .register stream
1820 with it.
1821 .
1822 .REQ .opena stream filename
1823 Like
1824 .request .open
1825 but append to it.
1826 .
1827 .REQ .os
1828 Output vertical distance that was saved by the
1829 .request sv
1830 request.
1831 .
1832 .REQ .pc
1833 Reset page number character to\~\c
1834 .squoted_char % .
1835 .
1836 .REQ .pc c
1837 Page number character.
1838 .
1839 .REQ .pi program
1840 Pipe output to
1841 .I program
1842 (nroff only).
1843 .
1844 .REQ .pl
1845 Set page length to default
1846 .scalednumber 11 i .
1847 The current page length is stored in
1848 .register .p .
1849 .
1850 .REQ .pl \[+-]N
1851 Change page length to
1852 .I \[+-]N
1853 (default scale indicator\~\c
1854 .scaleindicator v ).
1855 .
1856 .REQ .pm
1857 Print macro names and sizes (number of blocks of 128 bytes).
1858 .
1859 .REQ ".pm t"
1860 Print only total of sizes of macros (number of 128 bytes blocks).
1861 .
1862 .REQ .pn \[+-]N
1863 Next page number
1864 .IR N .
1865 .
1866 .REQ .pnr
1867 Print the names and contents of all currently defined number registers
1868 on stderr.
1869 .
1870 .REQ .po
1871 Change to previous page offset.
1872 .
1873 The current page offset is available in
1874 .register .o .
1875 .
1876 .REQ .po \[+-]N
1877 Page offset
1878 .IR N .
1879 .
1880 .REQ .ps
1881 Return to previous point-size.
1882 .REQ .ps \[+-]N
1883 Point size; same as
1884 .esc[] s \[+-]N .
1885 .
1886 .REQ .psbb filename
1887 Get the bounding box of a PostScript image
1888 .IR filename .
1889 .
1890 .REQ .pso command
1891 This behaves like the
1892 .request so
1893 request except that input comes from the standard output of
1894 .IR command .
1895 .
1896 .REQ .ptr
1897 Print the names and positions of all traps (not including input line
1898 traps and diversion traps) on stderr.
1899 .
1900 .REQ .pvs
1901 Change to previous post-vertical line spacing.
1902 .
1903 .REQ .pvs \[+-]N
1904 Change post-vertical line spacing according to
1905 .I \[+-]N
1906 (default scale indicator\~\c
1907 .scaleindicator p ).
1908 .
1909 .REQ .rchar c1 c2 .\|.\|.\&
1910 Remove the definitions of characters
1911 .IR c1 ,
1912 .IR c2 ,
1913 .I .\|.\|.\&
1914 .
1915 .REQ .rd prompt
1916 Read insertion.
1917 .
1918 .REQ .return
1919 Return from a macro.
1920 .
1921 .REQ .rj n
1922 Right justify the next
1923 .I n
1924 input lines.
1925 .
1926 .REQ .rm name
1927 Remove request, macro, or string
1928 .IR name .
1929 .
1930 .REQ .rn old new
1931 Rename request, macro, or string
1932 .I old
1933 to
1934 .IR new .
1935 .
1936 .REQ .rnn reg1 reg2
1937 Rename register
1938 .I reg1
1939 to
1940 .IR reg2 .
1941 .
1942 .REQ .rr register
1943 Remove
1944 .IR register .
1945 .
1946 .REQ .rs
1947 Restore spacing; turn no-space mode off.
1948 .
1949 .REQ .rt \[+-]N
1950 Return
1951 .I (upward only)
1952 to marked vertical place (default scale indicator\~\c
1953 .scaleindicator v ).
1954 .
1955 .REQ .shc
1956 Reset soft hyphen character to
1957 .esc (hy .
1958 .
1959 .REQ .shc c
1960 Set the soft hyphen character to
1961 .IR c .
1962 .
1963 .REQ .shift n
1964 In a macro, shift the arguments by
1965 .IR n \~\c
1966 positions.
1967 .
1968 .REQ .sizes s1 s2 .\|.\|.\& sn \fB[0]\fP
1969 Set available font sizes similar to the
1970 .B sizes
1971 command in a
1972 .B DESC
1973 file.
1974 .
1975 .REQ .so filename
1976 Include source file.
1977 .
1978 .REQ .sp
1979 Skip one line vertically.
1980 .
1981 .REQ .sp N
1982 Space vertical distance
1983 .I N
1984 up or down according to sign of
1985 .I N
1986 (default scaling indicator\~\c
1987 .scaleindicator v ).
1988 .
1989 .REQ .special s1 s2 .\|.\|.\&
1990 Fonts
1991 .IR s1 ,
1992 .IR s2 ,
1993 etc.\& are special and will be searched for characters not in the
1994 current font.
1995 .
1996 .REQ .ss N
1997 Space-character size set to
1998 .IR N /12
1999 of the spacewidth in the current font.
2000 .
2001 .REQ .ss N M
2002 Space-character size set to
2003 .IR N /12
2004 and sentence space size set to
2005 .IR M /12
2006 of the spacewidth in the current font (\f[CR]\[eq]1/3 em\f[]).
2007 .
2008 .REQ .sty n style
2009 Associate
2010 .I style
2011 with font position
2012 .IR n .
2013 .
2014 .REQ .substring register n1 n2
2015 Replace the string in
2016 .I register
2017 with the substring defined by the indices
2018 .I n1
2019 and
2020 .IR n2 .
2021 .
2022 .REQ .sv
2023 Save
2024 .scalednumber 1 v
2025 of vertical space.
2026 .
2027 .REQ .sv N
2028 Save the vertical distance
2029 .I N
2030 for later output with
2031 .request os
2032 request.
2033 .
2034 .REQ .sy command-line
2035 Execute program
2036 .IR command-line .
2037 .
2038 .REQ ".ta T" N
2039 Set tabs after every position that is a multiple of
2040 .I N
2041 (default scaling indicator\~\c
2042 .scaleindicator m ).
2043 .REQ .ta n1 n2 .\|.\|.\& nn \f[CB]T\f[] r1 r2 .\|.\|.\& rn
2044 Set tabs at positions
2045 .IR n1 ,
2046 .IR n2 ,
2047 .Text .\|.\|.,
2048 .IR nn ,
2049 then set tabs at
2050 .IR nn + r1 ,
2051 .IR nn + r2 ,
2052 .Text .\|.\|.,
2053 .IR nn + rn ,
2054 then at
2055 .IR nn + rn + r1 ,
2056 .IR nn + rn + r2 ,
2057 .Text .\|.\|.,
2058 .IR nn + rn + rn ,
2059 and so on.
2060 .
2061 .\".REQ .tar
2062 .\"Restore internally saved tab positions.
2063 .\".
2064 .\".REQ .tas
2065 .\"Save tab positions internally.
2066 .
2067 .REQ .tc
2068 Remove tab repition character.
2069 .REQ .tc c
2070 Set tab repetition character to\~\c
2071 .IR c .
2072 .
2073 .REQ .ti \[+-]N
2074 Temporary indent next line (default scaling indicator\~\c
2075 .scaleindicator m ).
2076 .
2077 .REQ .tkf font s1 n1 s2 n2
2078 Enable track kerning for
2079 .IR font .
2080 .
2081 .REQ .tl \f[CB]\[cq]\f[]left\f[CB]\[cq]\f[]center\f[CB]\[cq]\f[]right\f[CB]\[cq]\f[]
2082 Three-part title.
2083 .
2084 .REQ .tm anything
2085 Print
2086 .I anything
2087 on terminal (UNIX standard message output).
2088 .
2089 .REQ .tm1 anything
2090 Print
2091 .I anything
2092 on terminal (UNIX standard message output), allowing leading
2093 whitespace if
2094 .I anything
2095 starts with
2096 .character \[dq]
2097 (which will be stripped off).
2098 .
2099 .REQ .tmc anything
2100 Similar to
2101 .request .tm1
2102 without emitting a final newline.
2103 .
2104 .REQ .tr abcd.\|.\|.\&
2105 Translate
2106 .I a
2107 to
2108 .IR b ,
2109 .I c
2110 to
2111 .IR d ,
2112 etc.\& on output.
2113 .
2114 .REQ .trf filename
2115 Transparently output the contents of file
2116 .IR filename .
2117 .
2118 .REQ .trin abcd.\|.\|.\&
2119 This is the same as the
2120 .request tr
2121 request except that the
2122 .B asciify
2123 request will use the character code (if any) before the character
2124 translation.
2125 .
2126 .REQ .trnt abcd.\|.\|.\&
2127 This is the same as the
2128 .request tr
2129 request except that the translations do not apply to text that is
2130 transparently throughput into a diversion with
2131 .esc ! .
2132 .
2133 .REQ .troff
2134 Make the built-in condition
2135 .B t
2136 true and
2137 .B n
2138 false.
2139 .
2140 .REQ .uf font
2141 Underline font set to
2142 .I font
2143 (to be switched to by
2144 .request .ul ).
2145 .
2146 .REQ .ul N
2147 Underline (italicize in troff)
2148 .I N
2149 input lines.
2150 .
2151 .REQ .unformat diversion
2152 Unformat space characters and tabs, preserving font information in
2153 .IR diversion .
2154 .REQ .vpt n
2155 Enable vertical position traps if
2156 .I n
2157 is non-zero, disable them otherwise.
2158 .
2159 .REQ .vs
2160 Change to previous vertical base line spacing.
2161 .
2162 .REQ .vs \[+-]N
2163 Set vertical base line spacing according to
2164 .I \[+-]N
2165 (default scale indicator\~\c
2166 .scaleindicator p ).
2167 Default value is
2168 .scalednumber 12 p .
2169 .
2170 .REQ .warn n
2171 Set warnings code to
2172 .IR n .
2173 .
2174 .REQ .wh N trap
2175 Set location trap; negative means from page bottom.
2176 .
2177 .REQ .while cond anything
2178 While condition
2179 .I cond
2180 is true, accept
2181 .I anything
2182 as input.
2183 .
2184 .REQ .write stream anything
2185 Write
2186 .I anything
2187 to the stream named
2188 .IR stream .
2189 .
2190 .REQ .writec stream anything
2191 Similar to
2192 .request .write
2193 without emitting a final newline.
2194 .
2195 .REQ .writem stream xx
2196 Write contents of macro or string
2197 .I xx
2198 to the stream named
2199 .IR stream .
2200 .
2201 .PD
2202 .
2203 .P
2204 Besides these standard groff requests, there might be further macro
2205 calls.
2206 They can originate from a macro package (see
2207 .BR roff (@MAN7EXT@)
2208 for an overview) or from a preprocessor.
2209 .
2210 .P
2211 Preprocessor macros are easy to be recognized.
2212 .
2213 They enclose their code into a pair of characteristic macros.
2214 .
2215 .P
2216 .TS
2217 box, center, tab (@);
2218 c | c | c
2219 CfCB | CfCB | CfCB.
2220 preprocessor@start macro@ end macro
2221 =
2222 eqn@.PS@.PE
2223 grap@.G1@.G2
2224 grn@.GS@.GE
2225 pic@.PS@.PE
2226 refer@.R1@.R2
2227 soelim@\f[I]none@\f[I]none
2228 tbl@.TS@.TE
2229 .TE
2230 .P
2231 .
2232 .
2233 .\" --------------------------------------------------------------------
2234 .SH "ESCAPE SEQUENCES"
2235 .\" --------------------------------------------------------------------
2236 .
2237 Escape sequences are in-line language elements usually introduced by a
2238 backslash
2239 .squoted_char \[rs]
2240 and followed by an escape name and sometimes by a required argument.
2241 .
2242 Input processing is continued directly after the escaped character or
2243 the argument resp.\& without an intervening separation character.
2244 .
2245 So there must be a way to determine the end of the escape name and the
2246 end of the argument.
2247 .
2248 .P
2249 This is done by enclosing names (escape name and arguments consisting
2250 of a variable name) by a pair of brackets
2251 .BI \[lB] name \[rB]
2252 and constant arguments (number expressions and characters) by
2253 apostrophes (ASCII 0x27) like
2254 .BI \[cq] constant \[cq] \f[R].
2255 .
2256 .P
2257 There are abbreviations for short names.
2258 .
2259 Two character escape names can be specified by an opening parenthesis
2260 like
2261 .esc ( xy
2262 without a closing counterpart.
2263 .
2264 And all one-character names different from the special characters
2265 .squoted_char [
2266 and
2267 .squoted_char (
2268 can even be specified without a marker in the form
2269 .esc c .
2270 .
2271 .P
2272 Constant arguments of length\~1 can omit the marker apostrophes, too,
2273 but there is no two-character analogue.
2274 .
2275 .P
2276 While 1-character escape sequences are mainly used for in-line
2277 functions and system related tasks, the 2-letter names following the
2278 .esc (
2279 construct are used for special characters predefined by the roff system.
2280 .
2281 Escapes sequences with names of more than two characters
2282 .esc[] "" name
2283 denote user defined named characters (see the
2284 .request char
2285 request).
2286 .
2287 .
2288 .\" --------------------------------------------------------------------
2289 .SS "Single Character Escapes"
2290 .\" --------------------------------------------------------------------
2291 .
2292 .PD 0
2293 .
2294 .\" --------- comments ---------
2295 .
2296 .ESC \[dq]
2297 Beginning of a comment.
2298 .
2299 Everything up to the end of the line is ignored.
2300 .
2301 .ESC #
2302 Everything up to and including the next newline is ignored.
2303 .
2304 This is interpreted in copy mode.
2305 .
2306 This is like
2307 .esc \[dq]
2308 except that the terminating newline is ignored as well.
2309 .
2310 .\" --------- strings ---------
2311 .
2312 .ESC *\f[I]s\f[]
2313 The string stored in the string variable with 1-character name
2314 .IR s .
2315 .
2316 .ESC *(\f[I]st\f[]
2317 The string stored in the string variable with 2-character name
2318 .IR st .
2319 .
2320 .ESC[] * stringvar
2321 The string stored in the string variable with arbitrary length name
2322 .IR stringvar .
2323 .
2324 .\" --------- macro arguments ---------
2325 .
2326 .ESC $0
2327 The name by which the current macro was invoked.
2328 .
2329 The
2330 .request als
2331 request can make a macro have more than one name.
2332 .
2333 .ESC $ x
2334 Macro argument with 1-place number
2335 .IR x ,
2336 where
2337 .I x
2338 is a digit between 1 and 9.
2339 .
2340 .ESC $( xy
2341 Macro argument with 2-digit number
2342 .IR xy .
2343 .
2344 .ESC[] $ nexp
2345 Macro argument with number
2346 .IR nexp ,
2347 where
2348 .I nexp
2349 is a numerical expression evaluating to an integer \[>=]1.
2350 .
2351 .ESC $*
2352 In a macro, the concatenation of all the arguments separated by spaces.
2353 .
2354 .ESC $@
2355 In a macro, the concatenation of all the arguments with each surrounded
2356 by double quotes, and separated by spaces.
2357 .
2358 .\" --------- escaped characters ---------
2359 .
2360 .ESC \[rs]
2361 reduces to a single backslash; useful to delay its interpretation as
2362 escape character in copy mode.
2363 .
2364 For a printable backslash, use
2365 .esc e ,
2366 or even better
2367 .esc [rs] ,
2368 to be independent from the current escape character.
2369 .
2370 .ESC \[cq]
2371 The acute accent \[aa]; same as
2372 .esc (aa .
2373 Unescaped: apostrophe, right quotation mark, single quote (ASCII 0x27).
2374 .
2375 .ESC `
2376 The grave accent \[ga]; same as
2377 .esc (ga .
2378 Unescaped: left quote, backquote (ASCII 0x60).
2379 .
2380 .ESC \-
2381 The \- sign in the current font.
2382 .
2383 .ESC .
2384 An uninterpreted dot (period), even at start of line.
2385 .
2386 .ESC %
2387 Default optional hyphenation character.
2388 .
2389 .ESC !
2390 Transparent line indicator.
2391 .
2392 .ESC? anything
2393 In a diversion, this will transparently embed
2394 .I anything
2395 in the diversion.
2396 .I anything
2397 is read in copy mode.
2398 .
2399 See also the escape sequences
2400 .esc !
2401 and
2402 .esc ? .
2403 .
2404 .
2405 .\" --------- spacing ---------
2406 .
2407 .ESC \& space
2408 Unpaddable space-size space character (no line break).
2409 .
2410 .ESC 0
2411 Digit width.
2412 .
2413 .ESC |
2414 1/6\ em narrow space character; zero width in nroff.
2415 .
2416 .ESC ^
2417 1/12\ em half-narrow space character; zero width in nroff.
2418 .
2419 .ESC &
2420 Non-printable, zero width character.
2421 .
2422 .ESC )
2423 Like
2424 .esc &
2425 except that it behaves like a character declared with the cflags
2426 request to be transparent for the purposes of end of sentence
2427 recognition.
2428 .
2429 .ESC /
2430 Increases the width of the preceding character so that the spacing
2431 between that character and the following character will be correct if
2432 the following character is a roman character.
2433 .
2434 .ESC ,
2435 Modifies the spacing of the following character so that the spacing
2436 between that character and the preceding character will correct if the
2437 preceding character is a roman character.
2438 .
2439 .ESC ~
2440 Unbreakable space that stretches like a normal inter-word space when a
2441 line is adjusted.
2442 .
2443 .ESC :
2444 Inserts a zero-width break point (similar to
2445 .esc %
2446 but without a soft hyphen character).
2447 .
2448 .ESC "" newline
2449 Ignored newline, for continuation lines.
2450 .
2451 .\" --------- structuring ---------
2452 .
2453 .ESC {
2454 Begin conditional input.
2455 .
2456 .ESC }
2457 End conditional input.
2458 .
2459 .\" --------- longer escape names ---------
2460 .
2461 .ESC ( sc
2462 The special character with 2-character name
2463 .IR sc ,
2464 see section
2465 .BR "Special Characters" .
2466 .
2467 .ESC[] "" name
2468 The named character with arbitrary length name
2469 .IR name .
2470 .
2471 .\" --------- alphabetical escapes ---------
2472 .
2473 .ESC a
2474 Non-interpreted leader character.
2475 .
2476 .ESCq A anything
2477 If
2478 .I anything
2479 is acceptable as a name of a string, macro, diversion, register,
2480 environment or font it expands to\~1, and to\~0 otherwise.
2481 .
2482 .ESCq b abc.\|.\|.\&
2483 Bracket building function.
2484 .
2485 .ESCq B anything
2486 If
2487 .I anything
2488 is acceptable as a valid numeric expression it expands to\~1, and
2489 to\~0 otherwise.
2490 .
2491 .ESC c
2492 Interrupt text processing.
2493 .
2494 .ESCq C char
2495 The character called
2496 .IR char ;
2497 same as
2498 .esc[] "" char ,
2499 but compatible to other roff versions.
2500 .
2501 .ESC d
2502 Forward (down) 1/2 em vertical unit (1/2 line in nroff).
2503 .
2504 .ESCq D charseq
2505 Draw a graphical element defined by the characters in
2506 .IR charseq ;
2507 see groff info file for details.
2508 .
2509 .ESC e
2510 Printable version of the current escape character.
2511 .
2512 .ESC E
2513 Equivalent to an escape character, but is not interpreted in copy-mode.
2514 .
2515 .ESC f F
2516 Change to font with 1-character name or 1-digit number
2517 .IR F .
2518 .
2519 .ESC fP
2520 Switch back to previous font.
2521 .
2522 .ESC f( fo
2523 Change to font with 2-character name or 2-digit number
2524 .IR fo .
2525 .
2526 .ESC[] f font
2527 Change to font with arbitrary length name or number expression
2528 .IR font .
2529 .
2530 .ESC[] f ""
2531 Switch back to previous font.
2532 .
2533 .ESC F f
2534 Change to font family with 1-character name
2535 .IR f .
2536 .
2537 .ESC F( fm
2538 Change to font family with 2-character name
2539 .IR fm .
2540 .
2541 .ESC[] F fam
2542 Change to font family with arbitrary length name
2543 .IR fam .
2544 .
2545 .ESC[] F ""
2546 Switch back to previous font family.
2547 .
2548 .ESC[] g reg
2549 Return format of register with name
2550 .I reg
2551 suitable for
2552 .request .af .
2553 .
2554 Alternative forms
2555 .escarg g( xy
2556 and
2557 .escarg g x .
2558 .
2559 .ESCq h N
2560 Local horizontal motion; move right
2561 .I N
2562 (left if negative).
2563 .
2564 .ESCq H N
2565 Set height of current font to
2566 .IR N .
2567 .
2568 .ESC[] k reg
2569 Mark horizontal input place in register with arbitrary length name
2570 .IR reg .
2571 Alternative forms
2572 .escarg k( xy
2573 and
2574 .escarg k x .
2575 .
2576 .ESCq l Nc
2577 Horizontal line drawing function (optionally using character
2578 .IR c ).
2579 .
2580 .ESCq L Nc
2581 Vertical line drawing function (optionally using character
2582 .IR c ).
2583 .
2584 .ESC[] m color
2585 Change to color
2586 .IR color .
2587 .
2588 Alternative forms
2589 .escarg m( co
2590 and
2591 .escarg m c .
2592 .
2593 .ESC[] m ""
2594 Switch back to previous color.
2595 .
2596 .ESC[] M color
2597 Change filling color for closed drawn objects to color
2598 .IR color .
2599 .
2600 Alternative forms
2601 .escarg M( co
2602 and
2603 .escarg M c .
2604 .
2605 .ESC[] M ""
2606 Switch to previous fill color.
2607 .
2608 .ESC n r
2609 The numerical value stored in the register variable with the
2610 1-character name
2611 .IR r .
2612 .
2613 .ESC n( re
2614 The numerical value stored in the register variable with the
2615 2-character name
2616 .IR re .
2617 .
2618 .ESC[] n reg
2619 The numerical value stored in the register variable with arbitrary
2620 length name
2621 .IR reg .
2622 .
2623 .ESCq N n
2624 Typeset the character with code
2625 .I n
2626 in the current font, no special fonts are searched.
2627 .
2628 Useful for adding characters to a font using the
2629 .request char
2630 request.
2631 .
2632 .ESCq o abc.\|.\|.\&
2633 Overstrike characters
2634 .IR a ,
2635 .IR b ,
2636 .IR c ,
2637 etc.
2638 .
2639 .ESC O 0
2640 Disable glyph output.
2641 .
2642 Mainly for internal use.
2643 .
2644 .ESC O 1
2645 Enable glyph output.
2646 .
2647 Mainly for internal use.
2648 .
2649 .ESC p
2650 Break and spread output line.
2651 .
2652 .ESC r
2653 Reverse 1\ em vertical motion (reverse line in nroff).
2654 .
2655 .ESCq R "name\~\[+-]n"
2656 The same as
2657 .request .nr
2658 .I name
2659 .IR \[+-]n .
2660 .
2661 .ESC[] s \[+-]N
2662 Set the point size to
2663 .I N
2664 scaled points.
2665 .
2666 Note the alternative forms
2667 .BI \[rs]s \[+-] [ N ]\c
2668 ,
2669 .BI \[rs]s' \[+-]N '\c
2670 .Text ,
2671 .BI \[rs]s \[+-] ' N '\c
2672 .Text ,
2673 .escarg s( \[+-]xy\c
2674 .Text ,
2675 .BI \[rs]s \[+-] ( xy\c
2676 .Text ,
2677 .escarg s \[+-]x .
2678 Same as
2679 .request ps
2680 request.
2681 .
2682 .ESCq S N
2683 Slant output
2684 .I N
2685 degrees.
2686 .
2687 .ESC t
2688 Non-interpreted horizontal tab.
2689 .
2690 .ESC u
2691 Reverse (up) 1/2 em vertical motion (1/2 line in nroff).
2692 .
2693 .ESCq v N
2694 Local vertical motion; move down
2695 .I N
2696 (up if negative).
2697 .
2698 .ESC[] V env
2699 The contents of the environment variable
2700 .IR env .
2701 .
2702 Alternative forms
2703 .escarg V( xy
2704 and
2705 .escarg V x .
2706 .
2707 .ESCq w string
2708 The width of the character sequence
2709 .IR string .
2710 .
2711 .ESCq x N
2712 Extra line-space function (negative before, positive after).
2713 .
2714 .ESCq X string
2715 Output
2716 .I string
2717 as device control function.
2718 .
2719 .ESC[] Y name
2720 Output string variable or macro
2721 .I name
2722 uninterpreted as device control function.
2723 .
2724 Alternative forms
2725 .escarg Y( xy
2726 and
2727 .escarg Y x .
2728 .
2729 .ESC z c
2730 Print
2731 .I c
2732 with zero width (without spacing).
2733 .
2734 .ESCq Z anything
2735 Print
2736 .I anything
2737 and then restore the horizontal and vertical position;
2738 .I anything
2739 may not contain tabs or leaders.
2740 .
2741 .PD
2742 .P
2743 The escape sequences
2744 .esc e ,
2745 .esc . ,
2746 .esc \[dq] ,
2747 .esc $ ,
2748 .esc * ,
2749 .esc a ,
2750 .esc n ,
2751 .esc t ,
2752 .esc g ,
2753 and
2754 .escarg \& newline
2755 are interpreted in copy mode.
2756 .
2757 .P
2758 Escape sequences starting with
2759 .esc (
2760 or
2761 .esc [
2762 do not represent single character escape sequences, but introduce escape
2763 names with two or more characters.
2764 .
2765 .P
2766 If a backslash is followed by a character that does not constitute a
2767 defined escape sequence the backslash is silently ignored and the
2768 character maps to itself.
2769 .
2770 .
2771 .\" --------------------------------------------------------------------
2772 .SS "Special Characters"
2773 .\" --------------------------------------------------------------------
2774 .
2775 Common special characters are predefined by escape sequences of the
2776 form
2777 .BI \[rs]( xy
2778 with characters
2779 .I x
2780 and
2781 .IR y .
2782 .
2783 Some of these exist in the usual font while most of them are only
2784 available in the special font.
2785 .
2786 Below you'll find a selection of the most important glyphs; a complete
2787 list can be found in
2788 .BR groff_char (@MAN7EXT@).
2789 .RS
2790 .P
2791 .PD 0
2792 .
2793 .ESC (bu
2794 Bullet sign
2795 .ESC (co
2796 Copyright
2797 .ESC (ct
2798 Cent
2799 .ESC (dd
2800 Double dagger
2801 .ESC (de
2802 Degree
2803 .ESC (dg
2804 Dagger
2805 .ESC (rs
2806 Printable double quote
2807 .ESC (em
2808 Em-dash
2809 .ESC (hy
2810 Hyphen
2811 .ESC (rg
2812 Registered sign
2813 .ESC (rs
2814 Printable backslash character
2815 .ESC (sc
2816 Section sign
2817 .ESC (ul
2818 Underline character
2819 .ESC (==
2820 Identical
2821 .ESC (>=
2822 Larger or equal
2823 .ESC (<=
2824 Less or equal
2825 .ESC (!=
2826 Not equal
2827 .ESC (->
2828 Right arrow
2829 .ESC (<-
2830 Left arrow
2831 .ESC (+-
2832 Plus-minus sign
2833 .PD
2834 .RE
2835 .
2836 .
2837 .\" --------------------------------------------------------------------
2838 .SS "Strings"
2839 .\" --------------------------------------------------------------------
2840 .
2841 Strings are defined by the
2842 .request ds
2843 request and can be retrieved by the
2844 .esc *
2845 escape sequence.
2846 .
2847 .P
2848 Strings share their name space with macros.
2849 .
2850 So strings and macros without arguments are roughly equivalent, though
2851 calling a string like a macro and vice-versa is not stably implemented
2852 so far.
2853 .
2854 The following strings are predefined in groff.
2855 .
2856 .STRING .T
2857 The name of the current output device as specified by the
2858 .option -T
2859 command line option.
2860 .
2861 .
2862 .\" --------------------------------------------------------------------
2863 .SH REGISTERS
2864 .\" --------------------------------------------------------------------
2865 .
2866 Registers are variables that store a value.
2867 In groff, most registers store numerical values (see section
2868 .B NUMERICAL EXPRESSIONS
2869 above), but some can also hold a string value.
2870 .
2871 .P
2872 Each register is given a name.
2873 Arbitrary registers can be defined and set with the request
2874 .request nr
2875 .IR register .
2876 .
2877 .P
2878 The value stored in a register can be retrieved by the escape sequences
2879 introduced by
2880 .esc n .
2881 .
2882 .P
2883 Most useful are predefined registers.
2884 .
2885 In the following the notation
2886 .I name
2887 is used to refer to a register called
2888 .register name
2889 to make clear that we speak about registers.
2890 .
2891 Please keep in mind that the
2892 .esc[] n ""
2893 decoration is not part of the register name.
2894 .
2895 .
2896 .\" --------------------------------------------------------------------
2897 .SS "Read-only Registers"
2898 .\" --------------------------------------------------------------------
2899 .
2900 The following registers have predefined values that should not be
2901 modified by the user (usually, registers starting with a dot a
2902 read-only).
2903 .
2904 Mostly, they provide information on the current settings or store
2905 results from request calls.
2906 .
2907 .P
2908 .PD 0
2909 .
2910 .REG .$
2911 Number of arguments in the current macro.
2912 .
2913 .REG .a
2914 Post-line extra line-space most recently utilized using
2915 .escq x N .
2916 .
2917 .REG .A
2918 Set to\~1 in
2919 .B troff
2920 if option
2921 .B \-A
2922 is used; always\~1 in
2923 .BR nroff .
2924 .
2925 .REG .c
2926 Current input line number.
2927 .
2928 .REG .C
2929 1\~if compatibility mode is in effect, 0\~otherwise.
2930 .
2931 .REG .cdp
2932 The depth of the last character added to the current environment.
2933 It is positive if the character extends below the baseline.
2934 .
2935 .REG .ce
2936 The number of lines remaining to be centered, as set by the
2937 .request ce
2938 request.
2939 .
2940 .REG .cht
2941 The height of the last character added to the current environment.
2942 It is positive if the character extends above the baseline.
2943 .
2944 .REG .csk
2945 The skew of the last character added to the current environment.
2946 The skew of a character is how far to the right of the center of a character
2947 the center of an accent over that character should be placed.
2948 .
2949 .REG .d
2950 Current vertical place in current diversion; equal to register
2951 .register nl .
2952 .
2953 .REG .ev
2954 The name or number of the current environment (string-valued).
2955 .
2956 .REG .f
2957 Current font number.
2958 .
2959 .REG .fam
2960 The current font family (string-valued).
2961 .
2962 .REG .fn
2963 The current (internal) real font name (string-valued).
2964 .
2965 .REG .fp
2966 The number of the next free font position.
2967 .
2968 .REG .g
2969 Always 1 in GNU troff.
2970 .
2971 Macros should use it to test if running under groff.
2972 .
2973 .REG .h
2974 Text base-line high-water mark on current page or diversion.
2975 .
2976 .REG .H
2977 Available horizontal resolution in basic units.
2978 .
2979 .REG .hla
2980 The current hyphenation language as set by the
2981 .B .hla
2982 request.
2983 .
2984 .REG .hlc
2985 The number of immediately preceding consecutive hyphenated lines.
2986 .
2987 .REG .hlm
2988 The maximum allowed number of consecutive hyphenated lines, as set by
2989 the
2990 .request hlm
2991 request.
2992 .
2993 .REG .hy
2994 The current hyphenation flags (as set by the
2995 .request hy
2996 request).
2997 .
2998 .REG .hym
2999 The current hyphenation margin (as set by the
3000 .request hym
3001 request).
3002 .
3003 .REG .hys
3004 The current hyphenation space (as set by the
3005 .request hys
3006 request).
3007 .
3008 .REG .i
3009 Current ident.
3010 .
3011 .REG .in
3012 The indent that applies to the current output line.
3013 .
3014 .REG .int
3015 Positive if last output line contains
3016 .esc c .
3017 .
3018 .REG .kern
3019 1\~if pairwise kerning is enabled, 0\~otherwise.
3020 .
3021 .REG .l
3022 Current line length.
3023 .
3024 .REG .lg
3025 The current ligature mode (as set by the
3026 .request lg
3027 request).
3028 .
3029 .REG .linetabs
3030 The current line-tabs mode (as set by the
3031 .request linetabs
3032 request).
3033 .
3034 .REG .ll
3035 The line length that applies to the current output line.
3036 .
3037 .REG .lt
3038 The title length (as set by the
3039 .request lt
3040 request).
3041 .
3042 .REG .n
3043 Length of text portion on previous output line.
3044 .
3045 .REG .ne
3046 The amount of space that was needed in the last
3047 .request ne
3048 request that caused a trap to be sprung.
3049 .
3050 Useful in conjunction with
3051 .register .trunc .
3052 .
3053 .REG .ns
3054 1\~if in no-space mode, 0\~otherwise.
3055 .
3056 .REG .o
3057 Current page offset.
3058 .
3059 .REG .p
3060 Current page length.
3061 .
3062 .REG .pn
3063 The number of the next page: either the value set by a
3064 .request pn
3065 request, or the number of the current page plus\ 1.
3066 .
3067 .REG .ps
3068 The current pointsize in scaled points.
3069 .
3070 .REG .psr
3071 The last-requested pointsize in scaled points.
3072 .
3073 .REG .pvs
3074 The current post-vertical line spacing.
3075 .
3076 .REG .rj
3077 The number of lines to be right-justified as set by the rj request.
3078 .
3079 .REG .s
3080 Current point size as a decimal fraction.
3081 .
3082 .REG .sr
3083 The last requested pointsize in points as a decimal fraction
3084 (string-valued).
3085 .
3086 .REG .t
3087 Distance to the next trap.
3088 .
3089 .REG .T
3090 Set to\~1
3091 if option
3092 .B \-T
3093 is used.
3094 .
3095 .REG .tabs
3096 A string representation of the current tab settings suitable for use
3097 as an argument to the
3098 .request ta
3099 request.
3100 .
3101 .REG .trunc
3102 The amount of vertical space truncated by the most recently sprung
3103 vertical position trap, or, if the trap was sprung by a
3104 .request ne
3105 request, minus the amount of vertical motion produced by
3106 .request .ne .
3107 .
3108 In other words, at the point a trap is sprung, it represents
3109 the difference of what the vertical position would have been but for
3110 the trap, and what the vertical position actually is.
3111 .
3112 Useful in conjunction with the
3113 .register .ne
3114 register.
3115 .
3116 .REG .ss
3117 The value of the parameters set by the first argument of the
3118 .request ss
3119 request.
3120 .
3121 .REG .sss
3122 The value of the parameters set by the second argument of the
3123 .request ss
3124 request.
3125 .
3126 .REG .u
3127 Equal to 1 bin fill mode and 0 in nofill mode.
3128 .
3129 .REG .v
3130 Current vertical line spacing.
3131 .
3132 .REG .V
3133 Available vertical resolution in basic units.
3134 .
3135 .REG .vpt
3136 1\~ if vertical position traps are enabled, 0\~otherwise.
3137 .
3138 .REG .w
3139 Width of previous character.
3140 .
3141 .REG .warn
3142 The sum of the number codes of the currently enabled warnings.
3143 .
3144 .REG .x
3145 The major version number.
3146 .
3147 .REG .y
3148 The minor version number.
3149 .
3150 .REG .Y
3151 The revision number of groff.
3152 .
3153 .REG .z
3154 Name of current diversion.
3155 .PD
3156 .
3157 .
3158 .\" --------------------------------------------------------------------
3159 .SS "Writable Registers"
3160 .\" --------------------------------------------------------------------
3161 .
3162 The following registers can be read and written by the user.
3163 They have predefined default values, but these can be modified for
3164 customizing a document.
3165 .
3166 .P
3167 .PD 0
3168 .REG %
3169 Current page number.
3170 .
3171 .REG c.
3172 Current input line number.
3173 .
3174 .REG ct
3175 Character type (set by width function
3176 .esc w ).
3177 .
3178 .REG dl
3179 Maximal width of last completed diversion.
3180 .
3181 .REG dn
3182 Height of last completed diversion.
3183 .
3184 .REG dw
3185 Current day of week (1-7).
3186 .
3187 .REG dy
3188 Current day of month (1-31).
3189 .
3190 .REG hp
3191 Current horizontal position at input line.
3192 .
3193 .REG llx
3194 Lower left x-coordinate (in PostScript units) of a given PostScript
3195 image (set by
3196 .request .psbb ).
3197 .
3198 .REG lly
3199 Lower left y-coordinate (in PostScript units) of a given PostScript
3200 image (set by
3201 .request .psbb ).
3202 .
3203 .REG ln
3204 Output line number.
3205 .
3206 .REG mo
3207 Current month (1-12).
3208 .
3209 .REG nl
3210 Vertical position of last printed text base-line.
3211 .
3212 .REG rsb
3213 Like
3214 .register sb ,
3215 but takes account of the heights and depths of characters.
3216 .
3217 .REG rst
3218 Like
3219 .register st ,
3220 but takes account of the heights and depths of characters.
3221 .
3222 .REG sb
3223 Depth of string below base line (generated by width function
3224 .esc w ).
3225 .
3226 .REG skw
3227 Right skip width from the center of the last character in the
3228 .esc w
3229 argument.
3230 .
3231 .REG slimit
3232 If greater than 0, the maximum number of objects on the input stack.
3233 .
3234 If \[<=]0 there is no limit, i.e., recursion can continue until virtual
3235 memory is exhausted.
3236 .
3237 .REG ssc
3238 The amount of horizontal space (possibly negative) that should be
3239 added to the last character before a subscript (generated by width
3240 function
3241 .esc w ).
3242 .
3243 .REG st
3244 Height of string above base line (generated by width function
3245 .esc w ).
3246 .
3247 .REG systat
3248 The return value of the
3249 .I system()
3250 function executed by the last
3251 .request sy
3252 request.
3253 .
3254 .REG urx
3255 Upper right x-coordinate (in PostScript units) of a given PostScript
3256 image (set by
3257 .request .psbb ).
3258 .
3259 .REG ury
3260 Upper right y-coordinate (in PostScript units) of a given PostScript
3261 image (set by
3262 .request .psbb ).
3263 .
3264 .REG year
3265 The current year (year 2000 compliant).
3266 .
3267 .REG yr
3268 Current year minus 1900.
3269 .
3270 For Y2K compliance use register
3271 .register year
3272 instead.
3273 .
3274 .PD
3275 .
3276 .
3277 .\" --------------------------------------------------------------------
3278 .SH COMPATIBILITY
3279 .\" --------------------------------------------------------------------
3280 .
3281 The differences of the groff language in comparison to classical troff
3282 as defined by
3283 .I [CSTR\~#54]
3284 are documented in
3285 .BR groff_diff (@MAN7EXT@).
3286 .
3287 .P
3288 The groff system provides a compatibility mode, see
3289 .BR groff (@MAN1EXT@)
3290 on how to invoke this.
3291 .
3292 .
3293 .\" --------------------------------------------------------------------
3294 .SH BUGS
3295 .\" --------------------------------------------------------------------
3296 .
3297 Report bugs to the
3298 .MTO bug-groff@gnu.org "groff bug mailing list" .
3299 Include a complete, self-contained example that will allow the bug to
3300 be reproduced, and say which version of groff you are using.
3301 .
3302 .
3303 .\" --------------------------------------------------------------------
3304 .SH AUTHORS
3305 .\" --------------------------------------------------------------------
3306 .
3307 Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
3308 .
3309 .P
3310 This document is distributed under the terms of the FDL (GNU Free
3311 Documentation License) version 1.1 or later.
3312 .
3313 You should have received a copy of the FDL on your system, it is also
3314 available on-line at the
3315 .URL http://\:www.gnu.org/\:copyleft/\:fdl.html "GNU copyleft site" .
3316 .
3317 .P
3318 This document is part of
3319 .IR groff ,
3320 the GNU roff distribution.
3321 .
3322 It was written by
3323 .MTO bwarken@mayn.de "Bernd Warken" ;
3324 it is maintained by
3325 .MTO wl@gnu.org "Werner Lemberg" .
3326 .
3327 .
3328 .\" --------------------------------------------------------------------
3329 .SH "SEE ALSO"
3330 .\" --------------------------------------------------------------------
3331 .
3332 .P
3333 The main source of information for the groff language is the
3334 .B groff
3335 .BR info (1)
3336 file.
3337 .
3338 Besides the gory details, it contains many examples.
3339 .
3340 .TP
3341 .BR groff (@MAN1EXT@)
3342 the usage of the groff program and pointers to the documentation and
3343 availability of the groff system.
3344 .
3345 .TP
3346 .BR groff_diff (@MAN7EXT@)
3347 the differences of the groff language as compared to classical roff.
3348 .
3349 This is the authoritative document for the predefined language
3350 elements that are specific to groff.
3351 .
3352 .TP
3353 .BR groff_char (@MAN7EXT@)
3354 the predefined groff characters (glyphs).
3355 .
3356 .TP
3357 .BR groff_font (@MAN5EXT@)
3358 the specification of fonts and the DESC file.
3359 .
3360 .TP
3361 .BR roff (@MAN7EXT@)
3362 the history of roff, the common parts shared by all roff systems, and
3363 pointers to further documentation.
3364 .
3365 .TP
3366 .I [CSTR\~#54]
3367 .URL http://\:cm.bell-labs.com/\:cm/\:cs/\:54.ps \
3368 "Nroff/\:Troff User's Manual by Osanna & Kernighan"
3369 \[em] the bible for classical troff.
3370 .
3371 .
3372 .\" --------------------------------------------------------------------
3373 .\" Emacs Setup
3374 .\" --------------------------------------------------------------------
3375 .
3376 .\" Local Variables:
3377 .\" mode: nroff
3378 .\" End: