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1 .ig \"-*- nroff -*-
2 Copyright (C) 1989-1999 Free Software Foundation, Inc.
4 Permission is granted to make and distribute verbatim copies of
5 this manual provided the copyright notice and this permission notice
6 are preserved on all copies.
8 Permission is granted to copy and distribute modified versions of this
9 manual under the conditions for verbatim copying, provided that the
10 entire resulting derived work is distributed under the terms of a
11 permission notice identical to this one.
13 Permission is granted to copy and distribute translations of this
14 manual into another language, under the above conditions for modified
15 versions, except that this permission notice may be included in
16 translations approved by the Free Software Foundation instead of in
17 the original English.
18 ..
19 .\" define a string tx for the TeX logo
20 .ie t .ds tx T\h'-.1667m'\v'.224m'E\v'-.224m'\h'-.125m'X
21 .el .ds tx TeX
22 .de TQ
23 .br
24 .ns
25 .TP \\$1
26 ..
27 .\" Like TP, but if specified indent is more than half
28 .\" the current line-length - indent, use the default indent.
29 .de Tp
30 .ie \\n(.$=0:((0\\$1)*2u>(\\n(.lu-\\n(.iu)) .TP
31 .el .TP "\\$1"
32 ..
33 .\" The BSD man macros can't handle " in arguments to font change macros,
34 .\" so use \(ts instead of ".
35 .tr \(ts"
36 .TH @G@TROFF @MAN1EXT@ "@MDATE@" "Groff Version @VERSION@"
37 .SH NAME
38 @g@troff \- format documents
39 .SH SYNOPSIS
40 .nr a \n(.j
41 .ad l
42 .nr i \n(.i
43 .in +\w'\fB@g@troff 'u
44 .ti \niu
45 .B @g@troff
46 .de OP
47 .ie \\n(.$-1 .RI "[\ \fB\\$1\fP" "\\$2" "\ ]"
48 .el .RB "[\ " "\\$1" "\ ]"
49 ..
50 .OP \-abivzCERU
51 .OP \-w name
52 .OP \-W name
53 .OP \-d cs
54 .OP \-f fam
55 .OP \-m name
56 .OP \-n num
57 .OP \-o list
58 .OP \-r cn
59 .OP \-T name
60 .OP \-F dir
61 .OP \-M dir
62 .RI "[\ " files\|.\|.\|. "\ ]"
63 .br
64 .ad \na
65 .SH DESCRIPTION
66 This manual page describes the GNU version of
67 .BR troff ,
68 which is part of the groff document formatting system.
69 It is highly compatible with Unix troff.
70 Usually it should be invoked using the groff command, which will
71 also run preprocessors and postprocessors in the appropriate
72 order and with the appropriate options.
73 .SH OPTIONS
74 .TP \w'\-dname=s'u+2n
75 .B \-a
76 Generate an
77 .SM ASCII
78 approximation of the typeset output.
79 .TP
80 .B \-b
81 Print a backtrace with each warning or error message. This backtrace
82 should help track down the cause of the error. The line numbers given
83 in the backtrace may not always be correct:
84 .B troff 's
85 idea of line numbers
86 gets confused by
87 .B as
88 or
89 .B am
90 requests.
91 .TP
92 .B \-i
93 Read the standard input after all the named input files have been
94 processed.
95 .TP
96 .B \-v
97 Print the version number.
98 .TP
99 .BI \-w name
100 Enable warning
101 .IR name .
102 Available warnings are described in
103 the Warnings subsection below.
104 Multiple
105 .B \-w
106 options are allowed.
107 .TP
108 .BI \-W name
109 Inhibit warning
110 .IR name .
111 Multiple
112 .B \-W
113 options are allowed.
114 .TP
115 .B \-E
116 Inhibit all error messages.
117 .TP
118 .B \-z
119 Suppress formatted output.
120 .TP
121 .B \-C
122 Enable compatibility mode.
123 .TP
124 .BI \-d cs
125 .TQ
126 .BI \-d name = s
127 Define
128 .I c
129 or
130 .I name
131 to be a string
132 .IR s ;
133 .I c
134 must be a one letter name.
135 .TP
136 .BI \-f fam
137 Use
138 .I fam
139 as the default font family.
140 .TP
141 .BI \-m name
142 Read in the file
143 .BI tmac. name\fR.
144 Normally this will be searched for in @MACRODIR@.
145 By default is used the
146 .I safer
147 macro (reverted using -U ).
148 .TP
149 .B \-U
150 Unsafe option, avoids default use of
151 .I safer
152 macro.
153 .TP
154 .B \-R
155 Don't load
156 .BR troffrc .
157 .TP
158 .BI \-n num
159 Number the first page
160 .IR num .
161 .TP
162 .BI \-o list
163 Output only pages in
164 .IR list ,
165 which is a comma-separated list of page ranges;
166 .I n
167 means print page
168 .IR n ,
169 .IB m \- n
170 means print every page between
171 .I m
172 and
173 .IR n ,
174 .BI \- n
175 means print every page up to
176 .IR n ,
177 .IB n \-
178 means print every page from
179 .IR n .
180 .B Troff
181 will exit after printing the last page in the list.
182 .TP
183 .BI \-r cn
184 .TQ
185 .BI \-r name = n
186 Set number register
187 .I c
188 or
189 .I name
190 to
191 .IR n ;
192 .I c
193 must be a one character name;
194 .I n
195 can be any troff numeric expression.
196 .TP
197 .BI \-T name
198 Prepare output for device
199 .IR name ,
200 rather than the default
201 .BR @DEVICE@ .
202 .TP
203 .BI \-F dir
204 Search
205 .I dir
206 for subdirectories
207 .BI dev name
208 .RI ( name
209 is the name of the device)
210 for the
211 .B DESC
212 file and font files before the normal
213 .BR @FONTDIR@ .
214 .TP
215 .BI \-M dir
216 Search directory
217 .I dir
218 for macro files before the normal
219 .BR @MACRODIR@ .
220 .SH USAGE
221 Only the features not in Unix troff are described here.
222 .SS Long names
223 The names of number registers, fonts, strings/macros/diversions,
224 special characters can be of any length. In escape sequences, where
225 you can use
226 .BI ( xx
227 for a two character name, you can use
228 .BI [ xxx ]
229 for a name of arbitrary length:
230 .TP
231 .BI \e[ xxx ]
232 Print the special character called
233 .IR xxx .
234 .TP
235 .BI \ef[ xxx ]
236 Set font
237 .IR xxx .
238 .TP
239 .BI \e*[ xxx ]
240 Interpolate string
241 .IR xxx .
242 .TP
243 .BI \en[ xxx ]
244 Interpolate number register
245 .IR xxx .
246 .SS Fractional pointsizes
247 A
248 .I
249 scaled point
250 is equal to 1/sizescale
251 points, where
252 sizescale is specified in the
253 .B DESC
254 file (1 by default.)
255 There is a new scale indicator
256 .B z
257 which has the effect of multiplying by sizescale.
258 Requests and escape sequences in troff
259 interpret arguments that represent a pointsize as being in units
260 of scaled points, but they evaluate each such argument
261 using a default scale indicator of
262 .BR z .
263 Arguments treated in this way are
264 the argument to the
265 .B ps
266 request,
267 the third argument to the
268 .B cs
269 request,
270 the second and fourth arguments to the
271 .B tkf
272 request,
273 the argument to the
274 .B \eH
275 escape sequence,
276 and those variants of the
277 .B \es
278 escape sequence that take a numeric expression as their argument.
279 .LP
280 For example, suppose sizescale is 1000;
281 then a scaled point will be equivalent to a millipoint;
282 the request
283 .B .ps 10.25
284 is equivalent to
285 .B .ps 10.25z
286 and so sets the pointsize to 10250 scaled points,
287 which is equal to 10.25 points.
288 .LP
289 The number register
290 .B \en(.s
291 returns the pointsize in points as decimal fraction.
292 There is also a new number register
293 .B \en[.ps]
294 that returns the pointsize in scaled points.
295 .LP
296 It would make no sense to use the
297 .B z
298 scale indicator in a numeric expression
299 whose default scale indicator was neither
300 .B u
301 nor
302 .BR z ,
303 and so
304 .B troff
305 disallows this.
306 Similarly it would make no sense to use a scaling indicator
307 other than
308 .B z
309 or
310 .B u
311 in a numeric expression whose default scale indicator was
312 .BR z ,
313 and so
314 .B troff
315 disallows this as well.
316 .LP
317 There is also new scale indicator
318 .B s
319 which multiplies by the number of units in a scaled point.
320 So, for example,
321 .B \en[.ps]s
322 is equal to
323 .BR 1m .
324 Be sure not to confuse the
325 .B s
326 and
327 .B z
328 scale indicators.
329 .SS Numeric expressions
330 .LP
331 Spaces are permitted in a number expression within parentheses.
332 .LP
333 .B M
334 indicates a scale of 100ths of an em.
335 .TP
336 .IB e1 >? e2
337 The maximum of
338 .I e1
339 and
340 .IR e2 .
341 .TP
342 .IB e1 <? e2
343 The minimum of
344 .I e1
345 and
346 .IR e2 .
347 .TP
348 .BI ( c ; e )
349 Evaluate
350 .I e
351 using
352 .I c
353 as the default scaling indicator.
354 If
355 .I c
356 is missing, ignore scaling indicators in the evaluation of
357 .IR e .
358 .SS New escape sequences
359 .TP
360 .BI \eA' anything '
361 This expands to
362 .B 1
363 or
364 .B 0
365 according as
366 .I anything
367 is or is not acceptable as the name of a string, macro, diversion,
368 number register, environment or font.
369 It will return
370 .B 0
371 if
372 .I anything
373 is empty.
374 This is useful if you want to lookup user input in some sort of
375 associative table.
376 .TP
377 .BI \eC' xxx '
378 Typeset character named
379 .IR xxx .
380 Normally it is more convenient to use
381 .BI \e[ xxx ]\fR.
382 But
383 .B \eC
384 has the advantage that it is compatible with recent versions of
385 .SM UNIX
386 and is available in compatibility mode.
387 .TP
388 .B \eE
389 This is equivalent to an escape character,
390 but it's not interpreted in copy-mode.
391 For example, strings to start and end superscripting could be defined
392 like this:
393 .RS
394 .IP
395 \&.ds { \ev'\-.3m'\es'\eEn[.s]*6u/10u'
396 .br
397 \&.ds } \es0\ev'.3m'
398 .LP
399 The use of
400 .B \eE
401 ensures that these definitions will work even if
402 .B \e*{
403 gets interpreted in copy-mode
404 (for example, by being used in a macro argument.)
405 .RE
406 .TP
407 .BI \eN' n '
408 Typeset the character with code
409 .I n
410 in the current font.
411 .I n
412 can be any integer.
413 Most devices only have characters with codes between 0 and 255.
414 If the current font does not contain a character with that code,
415 special fonts will
416 .I not
417 be searched.
418 The
419 .B \eN
420 escape sequence can be conveniently used on conjunction with the
421 .B char
422 request:
423 .RS
424 .IP
425 .B
426 \&.char \e[phone] \ef(ZD\eN'37'
427 .RE
428 .IP
429 The code of each character is given in the fourth column in the font
430 description file after the
431 .B charset
432 command.
433 It is possible to include unnamed characters in the font description
434 file by using a name of
435 .BR \-\-\- ;
436 the
437 .B \eN
438 escape sequence is the only way to use these.
439 .TP
440 .BI \eR' name\ \(+-n '
441 This has the same effect as
442 .RS
443 .IP
444 .BI .nr\ name\ \(+-n
445 .RE
446 .TP
447 .BI \es( nn
448 .TQ
449 .BI \es\(+-( nn
450 Set the point size to
451 .I nn
452 points;
453 .I nn
454 must be exactly two digits.
455 .TP
456 .BI \es[\(+- n ]
457 .TQ
458 .BI \es\(+-[ n ]
459 .TQ
460 .BI \es'\(+- n '
461 .TQ
462 .BI \es\(+-' n '
463 Set the point size to
464 .I n
465 scaled points;
466 .I n
467 is a numeric expression with a default scale indicator of
468 .BR z .
469 .TP
470 .BI \eV x
471 .TQ
472 .BI \eV( xx
473 .TQ
474 .BI \eV[ xxx ]
475 Interpolate the contents of the environment variable
476 .I xxx ,
477 as returned by
478 .BR getenv (3).
479 .B \eV
480 is interpreted in copy-mode.
481 .TP
482 .BI \eY x
483 .TQ
484 .BI \eY( xx
485 .TQ
486 .BI \eY[ xxx ]
487 This is approximately equivalent to
488 .BI \eX'\e*[ xxx ]'\fR.
489 However the contents of the string or macro
490 .I xxx
491 are not interpreted;
492 also it is permitted for
493 .I xxx
494 to have been defined as a macro and thus contain newlines
495 (it is not permitted for the argument to
496 .B \eX
497 to contain newlines).
498 The inclusion of newlines requires an extension to the Unix troff output
499 format, and will confuse drivers that do not know about this
500 extension.
501 .TP
502 .BI \eZ' anything '
503 Print anything and then restore the horizontal and vertical
504 position;
505 .I anything
506 may not contain tabs or leaders.
507 .TP
508 .B \e$0
509 The name by which the current macro was invoked.
510 The
511 .B als
512 request can make a macro have more than one name.
513 .TP
514 .B \e$*
515 In a macro, the concatenation of all the arguments separated by spaces.
516 .TP
517 .B \e$@
518 In a macro, the concatenation of all the arguments with each surrounded by
519 double quotes, and separated by spaces.
520 .TP
521 .BI \e$( nn
522 .TQ
523 .BI \e$[ nnn ]
524 In a macro, this gives the
525 .IR nn -th
526 or
527 .IR nnn -th
528 argument.
529 Macros can have a unlimited number of arguments.
530 .TP
531 .BI \e? anything \e?
532 When used in a diversion, this will transparently embed
533 .I anything
534 in the diversion.
535 .I anything
536 is read in copy mode.
537 When the diversion is reread,
538 .I anything
539 will be interpreted.
540 .I anything
541 may not contain newlines; use
542 .B \e!
543 if you want to embed newlines in a diversion.
544 The escape sequence
545 .B \e?
546 is also recognised in copy mode and turned into a single internal
547 code; it is this code that terminates
548 .IR anything .
549 Thus
550 .RS
551 .RS
552 .ft B
553 .nf
554 .ne 15
555 \&.nr x 1
556 \&.nf
557 \&.di d
558 \e?\e\e?\e\e\e\e?\e\e\e\e\e\e\e\enx\e\e\e\e?\e\e?\e?
559 \&.di
560 \&.nr x 2
561 \&.di e
562 \&.d
563 \&.di
564 \&.nr x 3
565 \&.di f
566 \&.e
567 \&.di
568 \&.nr x 4
569 \&.f
570 .fi
571 .ft
572 .RE
573 .RE
574 .IP
575 will print
576 .BR 4 .
577 .TP
578 .B \e/
579 This increases the width of the preceding character so that
580 the spacing between that character and the following character
581 will be correct if the following character is a roman character.
582 For example, if an italic f is immediately followed by a roman
583 right parenthesis, then in many fonts the top right portion of the f
584 will overlap the top left of the right parenthesis producing \fIf\fR)\fR,
585 which is ugly.
586 Inserting
587 .B \e/
588 produces
589 .ie \n(.g \fIf\/\fR)\fR
590 .el \fIf\|\fR)\fR
591 and avoids this problem.
592 It is a good idea to use this escape sequence whenever an
593 italic character is immediately followed by a roman character without any
594 intervening space.
595 .TP
596 .B \e,
597 This modifies the spacing of the following character so that the spacing
598 between that character and the preceding character will correct if
599 the preceding character is a roman character.
600 For example, inserting
601 .B \e,
602 between the parenthesis and the f changes
603 \fR(\fIf\fR to
604 .ie \n(.g \fR(\,\fIf\fR.
605 .el \fR(\^\fIf\fR.
606 It is a good idea to use this escape sequence whenever a
607 roman character is immediately followed by an italic character without any
608 intervening space.
609 .TP
610 .B \e)
611 Like
612 .B \e&
613 except that it behaves like a character declared with the
614 .B cflags
615 request to be transparent for the purposes of end of sentence recognition.
616 .TP
617 .B \e~
618 This produces an unbreakable space that stretches like a normal inter-word
619 space when a line is adjusted.
620 .TP
621 .B \e#
622 Everything up to and including the next newline is ignored.
623 This is interpreted in copy mode.
624 This is like
625 .B \e"
626 except that
627 .B \e"
628 does not ignore the terminating newline.
629 .SS New requests
630 .TP
631 .BI .aln\ xx\ yy
632 Create an alias
633 .I xx
634 for number register object named
635 .IR yy .
636 The new name and the old name will be exactly equivalent.
637 If
638 .I yy
639 is undefined, a warning of type
640 .B reg
641 will be generated, and the request will be ignored.
642 .TP
643 .BI .als\ xx\ yy
644 Create an alias
645 .I xx
646 for request, string, macro, or diversion object named
647 .IR yy .
648 The new name and the old name will be exactly equivalent (it is similar to a
649 hard rather than a soft link).
650 If
651 .I yy
652 is undefined, a warning of type
653 .B mac
654 will be generated, and the request will be ignored.
655 The
656 .BR de ,
657 .BR am ,
658 .BR di ,
659 .BR da ,
660 .BR ds ,
661 and
662 .B as
663 requests only create a new object if the name of the macro, diversion
664 or string diversion is currently undefined or if it is defined to be a
665 request; normally they modify the value of an existing object.
666 .TP
667 .BI .asciify\ xx
668 This request only exists in order to make it possible
669 to make certain gross hacks work with GNU troff.
670 It `unformats' the diversion
671 .I xx
672 in such a way that
673 .SM ASCII
674 characters that were formatted and diverted into
675 .I xx
676 will be treated like ordinary input characters when
677 .I xx
678 is reread.
679 For example, this
680 .RS
681 .IP
682 .ne 7v+\n(.Vu
683 .ft B
684 .nf
685 .ss 24
686 \&.tr @.
687 \&.di x
688 \&@nr\e n\e 1
689 \&.br
690 \&.di
691 \&.tr @@
692 \&.asciify x
693 \&.x
694 .ss 12
695 .fi
696 .RE
697 .IP
698 will set register
699 .B n
700 to 1.
701 .TP
702 .B .backtrace
703 Print a backtrace of the input stack on stderr.
704 .TP
705 .BI .blm\ xx
706 Set the blank line macro to
707 .IR xx .
708 If there is a blank line macro,
709 it will be invoked when a blank line is encountered instead of the usual
710 troff behaviour.
711 .TP
712 .B .break
713 Break out of a while loop.
714 See also the
715 .B while
716 and
717 .B continue
718 requests.
719 Be sure not to confuse this with the
720 .B br
721 request.
722 .TP
723 .BI .cflags\ n\ c1\ c2\|.\|.\|.
724 Characters
725 .IR c1 ,
726 .IR c2 ,\|.\|.\|.
727 have properties determined by
728 .IR n ,
729 which is ORed from the following:
730 .RS
731 .TP
732 1
733 the character ends sentences
734 (initially characters
735 .B .?!
736 have this property);
737 .TP
738 2
739 lines can be broken before the character
740 (initially no characters have this property);
741 a line will not be broken at a character with this property
742 unless the characters on each side both have non-zero
743 hyphenation codes.
744 .TP
745 4
746 lines can be broken after the character
747 (initially characters
748 .B \-\e(hy\e(em
749 have this property);
750 a line will not be broken at a character with this property
751 unless the characters on each side both have non-zero
752 hyphenation codes.
753 .TP
754 8
755 the character overlaps horizontally
756 (initially characters
757 .B \e(ul\e(rn\e(ru
758 have this property);
759 .TP
760 16
761 the character overlaps vertically
762 (initially character
763 .B \e(br
764 has this property);
765 .TP
766 32
767 an end of sentence character followed by any number of characters
768 with this property will be treated
769 as the end of a sentence if followed by a newline or two spaces;
770 in other words
771 the character is transparent for the purposes of end of sentence
772 recognition;
773 this is the same as having a zero space factor in \*(tx
774 (initially characters
775 .B \(ts')]*\e(dg\e(rq
776 have this property).
777 .RE
778 .TP
779 .BI .char\ c\ string
780 Define character
781 .I c
782 to be
783 .IR string .
784 Every time character
785 .I c
786 needs to be printed,
787 .I string
788 will be processed in a temporary environment and the result
789 will be wrapped up into a single object.
790 Compatibility mode will be turned off
791 and the escape character will be set to
792 .B \e
793 while
794 .I string
795 is being processed.
796 Any emboldening, constant spacing or track kerning will be applied
797 to this object rather than to individual characters in
798 .IR string .
799 A character defined by this request can be used just like
800 a normal character provided by the output device.
801 In particular other characters can be translated to it
802 with the
803 .B tr
804 request;
805 it can be made the leader character by the
806 .B lc
807 request;
808 repeated patterns can be drawn with the character using the
809 .B \el
810 and
811 .B \eL
812 escape sequences;
813 words containing the character can be hyphenated
814 correctly, if the
815 .B hcode
816 request is used to give the character a hyphenation code.
817 There is a special anti-recursion feature:
818 use of character within the character's definition
819 will be handled like normal characters not defined with
820 .BR char .
821 A character definition can be removed with the
822 .B rchar
823 request.
824 .TP
825 .BI .chop\ xx
826 Chop the last character off macro, string, or diversion
827 .IR xx .
828 This is useful for removing the newline from the end of diversions
829 that are to be interpolated as strings.
830 .TP
831 .BI .close\ stream
832 Close the stream named
833 .IR stream ;
834 .I stream
835 will no longer be an acceptable argument to the
836 .B write
837 request.
838 See the
839 .B open
840 request.
841 .TP
842 .B .continue
843 Finish the current iteration of a while loop.
844 See also the
845 .B while
846 and
847 .B break
848 requests.
849 .TP
850 .BI .cp\ n
851 If
852 .I n
853 is non-zero or missing, enable compatibility mode, otherwise
854 disable it.
855 In compatibility mode, long names are not recognised, and the
856 incompatibilities caused by long names do not arise.
857 .TP
858 .BI .do\ xxx
859 Interpret
860 .I .xxx
861 with compatibility mode disabled.
862 For example,
863 .RS
864 .IP
865 .B
866 \&.do fam T
867 .LP
868 would have the same effect as
869 .IP
870 .B
871 \&.fam T
872 .LP
873 except that it would work even if compatibility mode had been enabled.
874 Note that the previous compatibility mode is restored before any files
875 sourced by
876 .I xxx
877 are interpreted.
878 .RE
879 .TP
880 .BI .evc\ xx
881 Copy the contents of environment
882 .I xx
883 to the current environment.
884 No pushing or popping of environents will be done.
885 .TP
886 .BI .fam\ xx
887 Set the current font family to
888 .IR xx .
889 The current font family is part of the current environment.
890 See the description of the
891 .B sty
892 request for more information on font families.
893 .TP
894 .BI .fspecial\ f\ s1\ s2\|.\|.\|.
895 When the current font is
896 .IR f ,
897 fonts
898 .IR s1 ,
899 .IR s2 ,\|.\|.\|.
900 will be special, that is, they will searched for characters not in
901 the current font.
902 Any fonts specified in the
903 .B special
904 request will be searched after fonts specified in the
905 .B fspecial
906 request.
907 .TP
908 .BI .ftr\ f\ g
909 Translate font
910 .I f
911 to
912 .IR g .
913 Whenever a font named
914 .I f
915 is referred to in
916 .B \ef
917 escape sequence,
918 or in the
919 .BR ft ,
920 .BR ul ,
921 .BR bd ,
922 .BR cs ,
923 .BR tkf ,
924 .BR special ,
925 .BR fspecial ,
926 .BR fp ,
927 or
928 .BR sty
929 requests,
930 font
931 .I g
932 will be used.
933 If
934 .I g
935 is missing,
936 or equal to
937 .I f
938 then font
939 .I f
940 will not be translated.
941 .TP
942 .BI .hcode \ c1\ code1\ c2\ code2\|.\|.\|.
943 Set the hyphenation code of character
944 .I c1
945 to
946 .I code1
947 and that of
948 .I c2
949 to
950 .IR code2 .
951 A hyphenation code must be a single input
952 character (not a special character) other than a digit or a space.
953 Initially each lower-case letter has a hyphenation code, which
954 is itself, and each upper-case letter has a hyphenation code
955 which is the lower case version of itself.
956 See also the
957 .B hpf
958 request.
959 .TP
960 .BI .hla\ lang
961 Set the current hyphenation language to
962 .IR lang .
963 Hyphenation exceptions specified with the
964 .B hw
965 request and hyphenation patterns specified with the
966 .B hpf
967 request are both associated with the current hyphenation language.
968 The
969 .B hla
970 request is usually invoked by the
971 .B troffrc
972 file.
973 .TP
974 .BI .hlm\ n
975 Set the maximum number of consecutive hyphenated lines to
976 .IR n .
977 If
978 .I n
979 is negative, there is no maximum.
980 The default value is \-1.
981 This value is associated with the current environment.
982 Only lines output from an environment count towards the maximum associated
983 with that environment.
984 Hyphens resulting from
985 .B \e%
986 are counted; explicit hyphens are not.
987 .TP
988 .BI .hpf\ file
989 Read hyphenation patterns from
990 .IR file ;
991 this will be searched for in the same way that
992 .BI tmac. name
993 is searched for when the
994 .BI \-m name
995 option is specified.
996 It should have the same format as the argument to
997 the \epatterns primitive in \*(tx;
998 the letters appearing in this file are interpreted as hyphenation
999 codes.
1000 A
1001 .B %
1002 character in the patterns file introduces a comment that continues
1003 to the end of the line.
1004 The set of hyphenation patterns is associated with the current language
1005 set by the
1006 .B hla
1007 request.
1008 The
1009 .B hpf
1010 request
1011 is usually invoked by the
1012 .B troffrc
1013 file.
1014 .TP
1015 .BI .hym\ n
1016 Set the
1017 .I hyphenation margin
1018 to
1019 .IR n :
1020 when the current adjustment mode is not
1021 .BR b ,
1022 the line will not be hyphenated if the line is no more than
1023 .I n
1024 short.
1025 The default hyphenation margin is 0.
1026 The default scaling indicator for this request is
1027 .IR m .
1028 The hyphenation margin is associated with the current environment.
1029 The current hyphenation margin is available in the
1030 .B \en[.hym]
1031 register.
1032 .TP
1033 .BI .hys\ n
1034 Set the
1035 .I hyphenation space
1036 to
1037 .IR n :
1038 when the current adjustment mode is
1039 .B b
1040 don't hyphenate the line if the line can be justified by adding no more than
1041 .I n
1042 extra space to each word space.
1043 The default hyphenation space is 0.
1044 The default scaling indicator for this request is
1045 .BR m .
1046 The hyphenation space is associated with the current environment.
1047 The current hyphenation space is available in the
1048 .B \en[.hys]
1049 register.
1050 .TP
1051 .BI .kern\ n
1052 If
1053 .I n
1054 is non-zero or missing, enable pairwise kerning, otherwise disable it.
1055 .TP
1056 .BI .length\ xx\ string
1057 Compute the length of
1058 .I string
1059 and return it in the number register
1060 .I xx
1061 (which is not necessarily defined before).
1062 .TP
1063 .BI .mso\ file
1064 The same as the
1065 .B so
1066 request except that
1067 .I file
1068 is searched for in the same way that
1069 .BI tmac. name
1070 is searched for when the
1071 .BI \-m name
1072 option is specified.
1073 .TP
1074 .B .nroff
1075 Make the
1076 .B n
1077 built-in condition true
1078 and the
1079 .B t
1080 built-in condition false.
1081 This can be reversed using the
1082 .B troff
1083 request.
1084 .TP
1085 .BI .open\ stream\ filename
1086 Open
1087 .I filename
1088 for writing and associate the stream named
1089 .I stream
1090 with it.
1091 See also the
1092 .B close
1093 and
1094 .B write
1095 requests.
1096 .TP
1097 .BI .opena\ stream\ filename
1098 Like
1099 .BR open ,
1100 but if
1101 .I filename
1102 exists, append to it instead of truncating it.
1103 .TP
1104 .B .pnr
1105 Print the names and contents of all currently defined number registers
1106 on stderr.
1107 .TP
1108 .BI .psbb \ filename
1109 Get the bounding box of a PostScript image
1110 .IR filename .
1111 This file must conform to Adobe's Document Structuring Conventions; the
1112 command looks for a
1113 .B %%BoundingBox
1114 comment to extract the bounding box values.
1115 After a successful call, the coordinates (in PostScript units) of the lower
1116 left and upper right corner can be found in the registers
1117 .BR \en[llx] ,
1118 .BR \en[lly] ,
1119 .BR \en[urx] ,
1120 and
1121 .BR \en[ury] ,
1122 respectively.
1123 If some error has occurred, the four registers are set to zero.
1124 .TP
1125 .BI .pso \ command
1126 This behaves like the
1127 .B so
1128 request except that input comes from the standard output of
1129 .IR command .
1130 .TP
1131 .B .ptr
1132 Print the names and positions of all traps (not including input line
1133 traps and diversion traps) on stderr. Empty slots in the page trap
1134 list are printed as well, because they can affect the priority of
1135 subsequently planted traps.
1136 .TP
1137 .BI .rchar\ c1\ c2\|.\|.\|.
1138 Remove the definitions of characters
1139 .IR c1 ,
1140 .IR c2 ,\|.\|.\|.
1141 This undoes the effect of a
1142 .B char
1143 request.
1144 .TP
1145 .B .rj
1146 .TQ
1147 .BI .rj\ n
1148 Right justify the next
1149 .I n
1150 input lines.
1151 Without an argument right justify the next input line.
1152 The number of lines to be right justified is available in the
1153 .B \en[.rj]
1154 register.
1155 This implicitly does
1156 .BR .ce\ 0 .
1157 The
1158 .B ce
1159 request implicitly does
1160 .BR .rj\ 0 .
1161 .TP
1162 .BI .rnn \ xx\ yy
1163 Rename number register
1164 .I xx
1165 to
1166 .IR yy .
1167 .TP
1168 .BI .shc\ c
1169 Set the soft hyphen character to
1170 .IR c .
1171 If
1172 .I c
1173 is omitted,
1174 the soft hyphen character will be set to the default
1175 .BR \e(hy .
1176 The soft hyphen character is the character which will be inserted
1177 when a word is hyphenated at a line break.
1178 If the soft hyphen character does not exist in the font of the character
1179 immediately preceding a potential break point,
1180 then the line will not be broken at that point.
1181 Neither definitions (specified with the
1182 .B char
1183 request)
1184 nor translations (specified with the
1185 .B tr
1186 request)
1187 are considered when finding the soft hyphen character.
1188 .TP
1189 .BI .shift\ n
1190 In a macro, shift the arguments by
1191 .I n
1192 positions:
1193 argument
1194 .I i
1195 becomes argument
1196 .IR i \- n ;
1197 arguments 1 to
1198 .I n
1199 will no longer be available.
1200 If
1201 .I n
1202 is missing,
1203 arguments will be shifted by 1.
1204 Shifting by negative amounts is currently undefined.
1205 .TP
1206 .BI .special\ s1\ s2\|.\|.\|.
1207 Fonts
1208 .IR s1 ,
1209 .IR s2 ,
1210 are special and will be searched for characters not in the
1211 current font.
1212 .TP
1213 .BI .sty\ n\ f
1214 Associate style
1215 .I f
1216 with font position
1217 .IR n .
1218 A font position can be associated either with a font or
1219 with a style.
1220 The current font is the index of a font position and so is also
1221 either a font or a style.
1222 When it is a style, the font that is actually used is the font the
1223 name of which is the concatenation of the name of the current family
1224 and the name of the current style.
1225 For example, if the current font is 1 and font position 1 is
1226 associated with style
1227 .B R
1228 and the current
1229 font family is
1230 .BR T ,
1231 then font
1232 .BR TR
1233 will be used.
1234 If the current font is not a style, then the current family is ignored.
1235 When the requests
1236 .BR cs ,
1237 .BR bd ,
1238 .BR tkf ,
1239 .BR uf ,
1240 or
1241 .B fspecial
1242 are applied to a style,
1243 then they will instead be applied to the member of the
1244 current family corresponding to that style.
1245 The default family can be set with the
1246 .B \-f
1247 option.
1248 The styles command in the
1249 .SM DESC
1250 file controls which font positions
1251 (if any) are initially associated with styles rather than fonts.
1252 .TP
1253 .BI .substring\ xx\ n1\ [ n2 ]
1254 Replace the string in register
1255 .I xx
1256 with the substring defined by the indices
1257 .I n1
1258 and
1259 .IR n2 .
1260 The first character in the string has index one.
1261 If
1262 .I n2
1263 is omitted, it is taken to be equal to the string's length. If the
1264 index value
1265 .I n1
1266 or
1267 .I n2
1268 is negative or zero, it will be counted from the end of the string,
1269 going backwards: The last character has index 0, the character before
1270 the last character has index -1, etc.
1271 .TP
1272 .BI .tkf\ f\ s1\ n1\ s2\ n2
1273 Enable track kerning for font
1274 .IR f .
1275 When the current font is
1276 .I f
1277 the width of every character will be increased by an amount
1278 between
1279 .I n1
1280 and
1281 .IR n2 ;
1282 when the current point size is less than or equal to
1283 .I s1
1284 the width will be increased by
1285 .IR n1 ;
1286 when it is greater than or equal to
1287 .I s2
1288 the width will be increased by
1289 .IR n2 ;
1290 when the point size is greater than or equal to
1291 .I s1
1292 and less than or equal to
1293 .I s2
1294 the increase in width is a linear function of the point size.
1295 .TP
1296 .BI .trf\ filename
1297 Transparently output the contents of file
1298 .IR filename .
1299 Each line is output as it would be were it preceded by
1300 .BR \e! ;
1301 however, the lines are not subject to copy-mode interpretation.
1302 If the file does not end with a newline, then a newline will
1303 be added.
1304 For example, you can define a macro
1305 .I x
1306 containing the contents of file
1307 .IR f ,
1308 using
1309 .RS
1310 .IP
1311 .BI .di\ x
1312 .br
1313 .BI .trf\ f
1314 .br
1315 .B .di
1316 .LP
1317 Unlike with the
1318 .B cf
1319 request,
1320 the file cannot contain characters such as
1321 .SM NUL
1322 that are not legal troff input characters.
1323 .RE
1324 .TP
1325 .B .trnt abcd
1326 This is the same as the
1327 .B tr
1328 request except that the translations do not apply to text that is
1329 transparently throughput into a diversion with
1330 .BR \e! .
1331 For example,
1332 .RS
1333 .LP
1334 .nf
1335 .ft B
1336 \&.tr ab
1337 \&.di x
1338 \e!.tm a
1339 \&.di
1340 \&.x
1341 .fi
1342 .ft
1343 .LP
1344 will print
1345 .BR b ;
1346 if
1347 .B trnt
1348 is used instead of
1349 .B tr
1350 it will print
1351 .BR a .
1352 .RE
1353 .TP
1354 .B .troff
1355 Make the
1356 .B n
1357 built-in condition false,
1358 and the
1359 .B t
1360 built-in condition true.
1361 This undoes the effect of the
1362 .B nroff
1363 request.
1364 .TP
1365 .BI .vpt\ n
1366 Enable vertical position traps if
1367 .I n
1368 is non-zero, disable them otherwise.
1369 Vertical position traps are traps set by the
1370 .B wh
1371 or
1372 .B dt
1373 requests.
1374 Traps set by the
1375 .B it
1376 request are not vertical position traps.
1377 The parameter that controls whether vertical position traps are enabled
1378 is global.
1379 Initially vertical position traps are enabled.
1380 .TP
1381 .BI .warn\ n
1382 Control warnings.
1383 .I n
1384 is the sum of the numbers associated with each warning that is to be enabled;
1385 all other warnings will be disabled.
1386 The number associated with each warning is listed in the `Warnings' section.
1387 For example,
1388 .B .warn 0
1389 will disable all warnings, and
1390 .B .warn 1
1391 will disable all warnings except that about missing characters.
1392 If
1393 .I n
1394 is not given,
1395 all warnings will be enabled.
1396 .TP
1397 .BI .while \ c\ anything
1398 While condition
1399 .I c
1400 is true, accept
1401 .I anything
1402 as input;
1403 .I c
1404 can be any condition acceptable to an
1405 .B if
1406 request;
1407 .I anything
1408 can comprise multiple lines if the first line starts with
1409 .B \e{
1410 and the last line ends with
1411 .BR \e} .
1412 See also the
1413 .B break
1414 and
1415 .B continue
1416 requests.
1417 .TP
1418 .BI .write\ stream\ anything
1419 Write
1420 .I anything
1421 to the stream named
1422 .IR stream .
1423 .I stream
1424 must previously have been the subject of an
1425 .B open
1426 request.
1427 .I anything
1428 is read in copy mode;
1429 a leading
1430 .B \(ts
1431 will be stripped.
1432 .SS Extended requests
1433 .TP
1434 .BI .cf\ filename
1435 When used in a diversion, this will embed in the diversion an object which,
1436 when reread, will cause the contents of
1437 .I filename
1438 to be transparently copied through to the output.
1439 In Unix troff, the
1440 contents of
1441 .I filename
1442 is immediately copied through to the output regardless of whether
1443 there is a current diversion; this behaviour is so anomalous that it
1444 must be considered a bug.
1445 .TP
1446 .BI .ev\ xx
1447 If
1448 .I xx
1449 is not a number, this will switch to a named environment called
1450 .IR xx .
1451 The environment should be popped with a matching
1452 .B ev
1453 request without any arguments, just as for numbered environments.
1454 There is no limit on the number of named environments; they will be
1455 created the first time that they are referenced.
1456 .TP
1457 .BI .fp\ n\ f1\ f2
1458 The
1459 .B fp
1460 request has an optional third argument.
1461 This argument gives the external name of the font,
1462 which is used for finding the font description file.
1463 The second argument gives the internal name of the font
1464 which is used to refer to the font in troff after it has been mounted.
1465 If there is no third argument then the internal name will be used
1466 as the external name.
1467 This feature allows you to use fonts with long names in compatibility mode.
1468 .TP
1469 .BI .ss\ m\ n
1470 When two arguments are given to the
1471 .B ss
1472 request, the second argument gives the
1473 .IR "sentence space size" .
1474 If the second argument is not given, the sentence space size
1475 will be the same as the word space size.
1476 Like the word space size, the sentence space is in units of
1477 one twelfth of the spacewidth parameter for the current font.
1478 Initially both the word space size and the sentence
1479 space size are 12.
1480 The sentence space size is used in two circumstances:
1481 if the end of a sentence occurs at the end of a line in fill mode, then
1482 both an inter-word space and a sentence space will be added;
1483 if two spaces follow the end of a sentence in the middle of a line,
1484 then the second space will be a sentence space.
1485 Note that the behaviour of Unix troff will be exactly
1486 that exhibited by GNU troff if a second argument is never given to the
1487 .B ss
1488 request.
1489 In GNU troff, as in Unix troff, you should always
1490 follow a sentence with either a newline or two spaces.
1491 .TP
1492 .BI .ta\ n1\ n2\|.\|.\|.nn \ T\ r1\ r2\|.\|.\|.\|rn
1493 Set tabs at positions
1494 .IR n1 ,
1495 .IR n2 ,\|.\|.\|.\|,
1496 .I nn
1497 and then set tabs at
1498 .IR nn + r1 ,
1499 .IR nn + r2 ,\|.\|.\|.\|.\|,
1500 .IR nn + rn
1501 and then at
1502 .IR nn + rn + r1 ,
1503 .IR nn + rn + r2 ,\|.\|.\|.\|,
1504 .IR nn + rn + rn ,
1505 and so on.
1506 For example,
1507 .RS
1508 .IP
1509 .B
1510 \&.ta T .5i
1511 .LP
1512 will set tabs every half an inch.
1513 .RE
1514 .SS New number registers
1515 The following read-only registers are available:
1516 .TP
1517 .B \en[.C]
1518 1 if compatibility mode is in effect, 0 otherwise.
1519 .TP
1520 .B \en[.cdp]
1521 The depth of the last character added to the current environment.
1522 It is positive if the character extends below the baseline.
1523 .TP
1524 .B \en[.ce]
1525 The number of lines remaining to be centered, as set by the
1526 .B ce
1527 request.
1528 .TP
1529 .B \en[.cht]
1530 The height of the last character added to the current environment.
1531 It is positive if the character extends above the baseline.
1532 .TP
1533 .B \en[.csk]
1534 The skew of the last character added to the current environment.
1535 The
1536 .I skew
1537 of a character is how far to the right of the center of a character
1538 the center of an accent over that character should be placed.
1539 .TP
1540 .B \en[.ev]
1541 The name or number of the current environment.
1542 This is a string-valued register.
1543 .TP
1544 .B \en[.fam]
1545 The current font family.
1546 This is a string-valued register.
1547 .TP
1548 .B \en[.fp]
1549 The number of the next free font position.
1550 .TP
1551 .B \en[.g]
1552 Always 1.
1553 Macros should use this to determine whether they are running
1554 under GNU troff.
1555 .TP
1556 .B \en[.hla]
1557 The current hyphenation language as set by the
1558 .B hla
1559 request.
1560 .TP
1561 .B \en[.hlc]
1562 The number of immediately preceding consecutive hyphenated lines.
1563 .TP
1564 .B \en[.hlm]
1565 The maximum allowed number of consecutive hyphenated lines, as set by the
1566 .B hlm
1567 request.
1568 .TP
1569 .B \en[.hy]
1570 The current hyphenation flags (as set by the
1571 .B hy
1572 request.)
1573 .TP
1574 .B \en[.hym]
1575 The current hyphenation margin (as set by the
1576 .B hym
1577 request.)
1578 .TP
1579 .B \en[.hys]
1580 The current hyphenation space (as set by the
1581 .B hys
1582 request.)
1583 .TP
1584 .B \en[.in]
1585 The indent that applies to the current output line.
1586 .TP
1587 .B \en[.kern]
1588 .B 1
1589 if pairwise kerning is enabled,
1590 .B 0
1591 otherwise.
1592 .TP
1593 .B \en[.lg]
1594 The current ligature mode (as set by the
1595 .B lg
1596 request.)
1597 .TP
1598 .B \en[.ll]
1599 The line length that applies to the current output line.
1600 .TP
1601 .B \en[.lt]
1602 The title length as set by the
1603 .B lt
1604 request.
1605 .TP
1606 .B \en[.ne]
1607 The amount of space that was needed in the last
1608 .B ne
1609 request that caused a trap to be sprung.
1610 Useful in conjunction with the
1611 .B \en[.trunc]
1612 register.
1613 .TP
1614 .B \en[.pn]
1615 The number of the next page:
1616 either the value set by a
1617 .B pn
1618 request, or the number of the current page plus 1.
1619 .TP
1620 .B \en[.ps]
1621 The current pointsize in scaled points.
1622 .TP
1623 .B \en[.psr]
1624 The last-requested pointsize in scaled points.
1625 .TP
1626 .B \en[.rj]
1627 The number of lines to be right-justified as set by the
1628 .B rj
1629 request.
1630 .TP
1631 .B \en[.sr]
1632 The last requested pointsize in points as a decimal fraction.
1633 This is a string-valued register.
1634 .TP
1635 .B \en[.tabs]
1636 A string representation of the current tab settings suitable for use as
1637 an argument to the
1638 .B ta
1639 request.
1640 .TP
1641 .B \en[.trunc]
1642 The amount of vertical space truncated by the most recently sprung
1643 vertical position trap, or,
1644 if the trap was sprung by a
1645 .B ne
1646 request,
1647 minus the amount of vertical motion produced by the
1648 .B ne
1649 request.
1650 In other words, at the point a trap is sprung, it represents the difference
1651 of what the vertical position would have been but for the trap,
1652 and what the vertical position actually is.
1653 Useful in conjunction with the
1654 .B \en[.ne]
1655 register.
1656 .TP
1657 .B \en[.ss]
1658 .TQ
1659 .B \en[.sss]
1660 These give the values of the parameters set by the
1661 first and second arguments of the
1662 .B ss
1663 request.
1664 .TP
1665 .B \en[.vpt]
1666 1 if vertical position traps are enabled, 0 otherwise.
1667 .TP
1668 .B \en[.warn]
1669 The sum of the numbers associated with each of the currently enabled
1670 warnings.
1671 The number associated with each warning is listed in the `Warnings'
1672 subsection.
1673 .TP
1674 .B \en(.x
1675 The major version number.
1676 For example, if the version number is
1677 .B 1.03
1678 then
1679 .B \en(.x
1680 will contain
1681 .BR 1 .
1682 .TP
1683 .B \en(.y
1684 The minor version number.
1685 For example, if the version number is
1686 .B 1.03
1687 then
1688 .B \en(.y
1689 will contain
1690 .BR 03 .
1691 .TP
1692 .B \en(.Y
1693 The revision number of groff.
1694 .TP
1695 .B \en[llx]
1696 .TQ
1697 .B \en[lly]
1698 .TQ
1699 .B \en[urx]
1700 .TQ
1701 .B \en[ury]
1702 These four registers are set by the
1703 .B \&.psbb
1704 request and contain the bounding box values (in PostScript units) of a given
1705 PostScript image.
1706 .LP
1707 The following registers are set by the
1708 .B \ew
1709 escape sequence:
1710 .TP
1711 .B \en[rst]
1712 .TQ
1713 .B \en[rsb]
1714 Like the
1715 .B st
1716 and
1717 .B sb
1718 registers, but takes account of the heights and depths of characters.
1719 .TP
1720 .B \en[ssc]
1721 The amount of horizontal space (possibly negative) that should
1722 be added to the last character before a subscript.
1723 .TP
1724 .B \en[skw]
1725 How far to right of the center of the last character
1726 in the
1727 .B \ew
1728 argument,
1729 the center of an accent from a roman font should be placed over that character.
1730 .LP
1731 The following read/write number registers are available:
1732 .TP
1733 .B \en[systat]
1734 The return value of the system() function executed by the last
1735 .B sy
1736 request.
1737 .TP
1738 .B \en[slimit]
1739 If greater than 0, the maximum number of objects on the input stack.
1740 If less than or equal to 0, there is no limit on the number of objects
1741 on the input stack. With no limit, recursion can continue until
1742 virtual memory is exhausted.
1743 .TP
1744 .B \en[year]
1745 The current year.
1746 Note that the traditional
1747 .B troff
1748 number register
1749 .B \en[yr]
1750 is the current year minus 1900.
1751 .SS Miscellaneous
1752 .LP
1753 Fonts not listed in the
1754 .SM DESC
1755 file are automatically mounted on the next available font position
1756 when they are referenced.
1757 If a font is to be mounted explicitly with the
1758 .B fp
1759 request on an unused font position,
1760 it should be mounted on the first unused font position,
1761 which can be found in the
1762 .B \en[.fp]
1763 register;
1764 although
1765 .B troff
1766 does not enforce this strictly,
1767 it will not allow a font to be mounted at a position whose number is much
1768 greater than that of any currently used position.
1769 .LP
1770 Interpolating a string does not hide existing macro arguments.
1771 Thus in a macro, a more efficient way of doing
1772 .IP
1773 .BI . xx\ \e\e$@
1774 .LP
1775 is
1776 .IP
1777 .BI \e\e*[ xx ]\e\e
1778 .LP
1779 If the font description file contains pairwise kerning information,
1780 characters from that font will be kerned.
1781 Kerning between two characters can be inhibited by placing a
1782 .B \e&
1783 between them.
1784 .LP
1785 In a string comparison in a condition,
1786 characters that appear at different input levels
1787 to the first delimiter character will not be recognised
1788 as the second or third delimiters.
1789 This applies also to the
1790 .B tl
1791 request.
1792 In a
1793 .B \ew
1794 escape sequence,
1795 a character that appears at a different input level to
1796 the starting delimiter character will not be recognised
1797 as the closing delimiter character.
1798 When decoding a macro argument that is delimited
1799 by double quotes, a character that appears at a different
1800 input level to the starting delimiter character will not
1801 be recognised as the closing delimiter character.
1802 The implementation of
1803 .B \e$@
1804 ensures that the double quotes surrounding an argument
1805 will appear the same input level, which will be different
1806 to the input level of the argument itself.
1807 In a long escape name
1808 .B ]
1809 will not be recognized as a closing delimiter except
1810 when it occurs at the same input level as the opening
1811 .BR ] .
1812 In compatibility mode, no attention is paid to the input-level.
1813 .LP
1814 There are some new types of condition:
1815 .TP
1816 .BI .if\ r xxx
1817 True if there is a number register named
1818 .IR xxx .
1819 .TP
1820 .BI .if\ d xxx
1821 True if there is a string, macro, diversion, or request named
1822 .IR xxx .
1823 .TP
1824 .BI .if\ c ch
1825 True if there is a character
1826 .IR ch
1827 available;
1828 .I ch
1829 is either an
1830 .SM ASCII
1831 character
1832 or a special character
1833 .BI \e( xx
1834 or
1835 .BI \e[ xxx ]\fR;
1836 the condition will also be true if
1837 .I ch
1838 has been defined by the
1839 .B char
1840 request.
1841 .SS Warnings
1842 The warnings that can be given by
1843 .B troff
1844 are divided into the following categories.
1845 The name associated with each warning is used by the
1846 .B \-w
1847 and
1848 .B \-W
1849 options;
1850 the number is used by the
1851 .B warn
1852 request, and by the
1853 .B .warn
1854 register.
1855 .nr x \w'\fBright-brace'+1n+\w'0000'u
1856 .ta \nxuR
1857 .TP \nxu+3n
1858 .BR char \t1
1859 Non-existent characters.
1860 This is enabled by default.
1861 .TP
1862 .BR number \t2
1863 Invalid numeric expressions.
1864 This is enabled by default.
1865 .TP
1866 .BR break \t4
1867 In fill mode, lines which could not be broken so that their length was
1868 less than the line length.
1869 This is enabled by default.
1870 .TP
1871 .BR delim \t8
1872 Missing or mismatched closing delimiters.
1873 .TP
1874 .BR el \t16
1875 Use of the
1876 .B el
1877 request with no matching
1878 .B ie
1879 request.
1880 .TP
1881 .BR scale \t32
1882 Meaningless scaling indicators.
1883 .TP
1884 .BR range \t64
1885 Out of range arguments.
1886 .TP
1887 .BR syntax \t128
1888 Dubious syntax in numeric expressions.
1889 .TP
1890 .BR di \t256
1891 Use of
1892 .B di
1893 or
1894 .B da
1895 without an argument when there is no current diversion.
1896 .TP
1897 .BR mac \t512
1898 Use of undefined strings, macros and diversions.
1899 When an undefined string, macro or diversion is used,
1900 that string is automatically defined as empty.
1901 So, in most cases, at most one warning will be given for
1902 each name.
1903 .TP
1904 .BR reg \t1024
1905 Use of undefined number registers.
1906 When an undefined number register is used,
1907 that register is automatically defined to have a value of 0.
1908 a definition is automatically made with a value of 0.
1909 So, in most cases, at most one warning will be given for
1910 use of a particular name.
1911 .TP
1912 .BR tab \t2048
1913 Inappropriate use of a tab character.
1914 Either use of a tab character where a number was expected,
1915 or use of tab character in an unquoted macro argument.
1916 .TP
1917 .BR right-brace \t4096
1918 Use of
1919 .B \e}
1920 where a number was expected.
1921 .TP
1922 .BR missing \t8192
1923 Requests that are missing non-optional arguments.
1924 .TP
1925 .BR input \t16384
1926 Illegal input characters.
1927 .TP
1928 .BR escape \t32768
1929 Unrecognized escape sequences.
1930 When an unrecognized escape sequence is encountered,
1931 the escape character is ignored.
1932 .TP
1933 .BR space \t65536
1934 Missing space between a request or macro and its argument.
1935 This warning will be given
1936 when an undefined name longer than two characters is encountered,
1937 and the first two characters of the name make a defined name.
1938 The request or macro will not be invoked.
1939 When this warning is given, no macro is automatically defined.
1940 This is enabled by default.
1941 This warning will never occur in compatibility mode.
1942 .TP
1943 .BR font \t131072
1944 Non-existent fonts.
1945 This is enabled by default.
1946 .TP
1947 .BR ig \t262144
1948 Illegal escapes in text ignored with the
1949 .B ig
1950 request.
1951 These are conditions that are errors when they do not occur
1952 in ignored text.
1953 .LP
1954 There are also names that can be used to refer to groups of warnings:
1955 .TP
1956 .B all
1957 All warnings except
1958 .BR di ,
1959 .B mac
1960 and
1961 .BR reg .
1962 It is intended that this covers all warnings
1963 that are useful with traditional macro packages.
1964 .TP
1965 .B w
1966 All warnings.
1967 .SS Incompatibilities
1968 .LP
1969 Long names cause some incompatibilities.
1970 Unix troff will interpret
1971 .IP
1972 .B
1973 \&.dsabcd
1974 .LP
1975 as defining a string
1976 .B ab
1977 with contents
1978 .BR cd .
1979 Normally, GNU troff will interpret this as a call of a macro named
1980 .BR dsabcd .
1981 Also Unix troff will interpret
1982 .B \e*[
1983 or
1984 .B \en[
1985 as references to a string or number register called
1986 .BR [ .
1987 In GNU troff, however, this will normally be interpreted as the start
1988 of a long name.
1989 In
1990 .I compatibility mode
1991 GNU troff will interpret these things in the traditional way.
1992 In compatibility mode, however, long names are not recognised.
1993 Compatibility mode can be turned on with the
1994 .B \-C
1995 command line option, and turned on or off with the
1996 .B cp
1997 request.
1998 The number register
1999 .B \en(.C
2000 is 1 if compatibility mode is on, 0 otherwise.
2001 .LP
2002 GNU troff
2003 does not allow the use of the escape sequences
2004 .BR \\e\e|\e^\e&\e}\e{\e (space) \e'\e`\e-\e_\e!\e%\ec
2005 in names of strings, macros, diversions, number registers,
2006 fonts or environments; Unix troff does.
2007 The
2008 .B \eA
2009 escape sequence may be helpful in avoiding use of these
2010 escape sequences in names.
2011 .LP
2012 Fractional pointsizes cause one noteworthy incompatibility.
2013 In Unix troff the
2014 .B ps
2015 request ignores scale indicators and so
2016 .IP
2017 .B .ps\ 10u
2018 .LP
2019 will set the pointsize to 10 points, whereas in
2020 GNU troff it will set the pointsize to 10 scaled points.
2021 .LP
2022 In GNU troff there is a fundamental difference between unformatted,
2023 input characters, and formatted, output characters.
2024 Everything that affects how an output character
2025 will be output is stored with the character; once an output
2026 character has been constructed it is unaffected by any subsequent
2027 requests that are executed, including
2028 .BR bd ,
2029 .BR cs ,
2030 .BR tkf ,
2031 .BR tr ,
2032 or
2033 .B fp
2034 requests.
2035 Normally output characters are constructed from input
2036 characters at the moment immediately before the character
2037 is added to the current output line.
2038 Macros, diversions and strings are all, in fact, the same type
2039 of object; they contain lists of input characters and output
2040 characters in any combination.
2041 An output character does not behave like an input character
2042 for the purposes of macro processing; it does not inherit any
2043 of the special properties that the input character from which it
2044 was constructed might have had.
2045 For example,
2046 .IP
2047 .nf
2048 .ft B
2049 \&.di x
2050 \e\e\e\e
2051 \&.br
2052 \&.di
2053 \&.x
2054 .ft
2055 .fi
2056 .LP
2057 will print
2058 .B \e\e
2059 in GNU troff;
2060 each pair of input
2061 .BR \e s
2062 is turned into one output
2063 .B \e
2064 and the resulting output
2065 .BR \e s
2066 are not interpreted as escape characters when they are reread.
2067 Unix troff would interpret them as escape characters
2068 when they were reread and would end up printing one
2069 .BR \e .
2070 The correct way to obtain a printable
2071 .B \e
2072 is to use the
2073 .B \ee
2074 escape sequence: this will always print a single instance of the
2075 current escape character, regardless of whether or not it is used in a
2076 diversion; it will also work in both GNU troff and Unix troff.
2077 If you wish for some reason to store in a diversion an escape
2078 sequence that will be interpreted when the diversion is reread,
2079 you can either use the traditional
2080 .B \e!
2081 transparent output facility, or, if this is unsuitable, the new
2082 .B \e?
2083 escape sequence.
2084 .SH ENVIRONMENT
2085 .TP
2086 .SM
2087 .B GROFF_TMAC_PATH
2088 A colon separated list of directories in which to search for
2089 macro files.
2090 .TP
2091 .SM
2092 .B GROFF_TYPESETTER
2093 Default device.
2094 .TP
2095 .SM
2096 .B GROFF_FONT_PATH
2097 A colon separated list of directories in which to search for the
2098 .BI dev name
2099 directory.
2100 .B troff
2101 will search in directories given in the
2102 .B \-F
2103 option before these, and in standard directories
2104 .RB ( @FONTPATH@ )
2105 after these.
2106 .SH FILES
2107 .Tp \w'@FONTDIR@/devname/DESC'u+3n
2108 .B @MACRODIR@/troffrc
2109 Initialization file
2110 .TP
2111 .BI @MACRODIR@/tmac. name
2112 Macro files
2113 .TP
2114 .BI @FONTDIR@/dev name /DESC
2115 Device description file for device
2116 .IR name .
2117 .TP
2118 .BI @FONTDIR@/dev name / F
2119 Font file for font
2120 .I F
2121 of device
2122 .IR name .
2123 .SH "SEE ALSO"
2124 .BR groff (@MAN1EXT@),
2125 .BR @g@tbl (@MAN1EXT@),
2126 .BR @g@pic (@MAN1EXT@),
2127 .BR @g@eqn (@MAN1EXT@),
2128 .BR @g@refer (@MAN1EXT@),
2129 .BR @g@soelim (@MAN1EXT@),
2130 .BR @g@grn (@MAN1EXT@),
2131 .BR grops (@MAN1EXT@),
2132 .BR grodvi (@MAN1EXT@),
2133 .BR grotty (@MAN1EXT@),
2134 .BR grohtml (@MAN1EXT@),
2135 .BR grolj4 (@MAN1EXT@),
2136 .BR groff_font (@MAN5EXT@),
2137 .BR groff_out (@MAN5EXT@),
2138 .BR groff_char (@MAN7EXT@)