| blob | 402d2a87981b100b63cca8e5ed12dbaeb232fb7e |
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 1 "@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 .fam\ xx
881 Set the current font family to
882 .IR xx .
883 The current font family is part of the current environment.
884 See the description of the
885 .B sty
886 request for more information on font families.
887 .TP
888 .BI .fspecial\ f\ s1\ s2\|.\|.\|.
889 When the current font is
890 .IR f ,
891 fonts
892 .IR s1 ,
893 .IR s2 ,\|.\|.\|.
894 will be special, that is, they will searched for characters not in
895 the current font.
896 Any fonts specified in the
897 .B special
898 request will be searched after fonts specified in the
899 .B fspecial
900 request.
901 .TP
902 .BI .ftr\ f\ g
903 Translate font
904 .I f
905 to
906 .IR g .
907 Whenever a font named
908 .I f
909 is referred to in
910 .B \ef
911 escape sequence,
912 or in the
913 .BR ft ,
914 .BR ul ,
915 .BR bd ,
916 .BR cs ,
917 .BR tkf ,
918 .BR special ,
919 .BR fspecial ,
920 .BR fp ,
921 or
922 .BR sty
923 requests,
924 font
925 .I g
926 will be used.
927 If
928 .I g
929 is missing,
930 or equal to
931 .I f
932 then font
933 .I f
934 will not be translated.
935 .TP
936 .BI .hcode \ c1\ code1\ c2\ code2\|.\|.\|.
937 Set the hyphenation code of character
938 .I c1
939 to
940 .I code1
941 and that of
942 .I c2
943 to
944 .IR code2 .
945 A hyphenation code must be a single input
946 character (not a special character) other than a digit or a space.
947 Initially each lower-case letter has a hyphenation code, which
948 is itself, and each upper-case letter has a hyphenation code
949 which is the lower case version of itself.
950 See also the
951 .B hpf
952 request.
953 .TP
954 .BI .hla\ lang
955 Set the current hyphenation language to
956 .IR lang .
957 Hyphenation exceptions specified with the
958 .B hw
959 request and hyphenation patterns specified with the
960 .B hpf
961 request are both associated with the current hyphenation language.
962 The
963 .B hla
964 request is usually invoked by the
965 .B troffrc
966 file.
967 .TP
968 .BI .hlm\ n
969 Set the maximum number of consecutive hyphenated lines to
970 .IR n .
971 If
972 .I n
973 is negative, there is no maximum.
974 The default value is \-1.
975 This value is associated with the current environment.
976 Only lines output from an environment count towards the maximum associated
977 with that environment.
978 Hyphens resulting from
979 .B \e%
980 are counted; explicit hyphens are not.
981 .TP
982 .BI .hpf\ file
983 Read hyphenation patterns from
984 .IR file ;
985 this will be searched for in the same way that
986 .BI tmac. name
987 is searched for when the
988 .BI \-m name
989 option is specified.
990 It should have the same format as the argument to
991 the \epatterns primitive in \*(tx;
992 the letters appearing in this file are interpreted as hyphenation
993 codes.
994 A
995 .B %
996 character in the patterns file introduces a comment that continues
997 to the end of the line.
998 The set of hyphenation patterns is associated with the current language
999 set by the
1000 .B hla
1001 request.
1002 The
1003 .B hpf
1004 request
1005 is usually invoked by the
1006 .B troffrc
1007 file.
1008 .TP
1009 .BI .hym\ n
1010 Set the
1011 .I hyphenation margin
1012 to
1013 .IR n :
1014 when the current adjustment mode is not
1015 .BR b ,
1016 the line will not be hyphenated if the line is no more than
1017 .I n
1018 short.
1019 The default hyphenation margin is 0.
1020 The default scaling indicator for this request is
1021 .IR m .
1022 The hyphenation margin is associated with the current environment.
1023 The current hyphenation margin is available in the
1024 .B \en[.hym]
1025 register.
1026 .TP
1027 .BI .hys\ n
1028 Set the
1029 .I hyphenation space
1030 to
1031 .IR n :
1032 when the current adjustment mode is
1033 .B b
1034 don't hyphenate the line if the line can be justified by adding no more than
1035 .I n
1036 extra space to each word space.
1037 The default hyphenation space is 0.
1038 The default scaling indicator for this request is
1039 .BR m .
1040 The hyphenation space is associated with the current environment.
1041 The current hyphenation space is available in the
1042 .B \en[.hys]
1043 register.
1044 .TP
1045 .BI .kern\ n
1046 If
1047 .I n
1048 is non-zero or missing, enable pairwise kerning, otherwise disable it.
1049 .TP
1050 .BI .length\ xx\ string
1051 Compute the length of
1052 .I string
1053 and return it in the number register
1054 .I xx
1055 (which is not necessarily defined before).
1056 .TP
1057 .BI .mso\ file
1058 The same as the
1059 .B so
1060 request except that
1061 .I file
1062 is searched for in the same way that
1063 .BI tmac. name
1064 is searched for when the
1065 .BI \-m name
1066 option is specified.
1067 .TP
1068 .B .nroff
1069 Make the
1070 .B n
1071 built-in condition true
1072 and the
1073 .B t
1074 built-in condition false.
1075 This can be reversed using the
1076 .B troff
1077 request.
1078 .TP
1079 .BI .open\ stream\ filename
1080 Open
1081 .I filename
1082 for writing and associate the stream named
1083 .I stream
1084 with it.
1085 See also the
1086 .B close
1087 and
1088 .B write
1089 requests.
1090 .TP
1091 .BI .opena\ stream\ filename
1092 Like
1093 .BR open ,
1094 but if
1095 .I filename
1096 exists, append to it instead of truncating it.
1097 .TP
1098 .B .pnr
1099 Print the names and contents of all currently defined number registers
1100 on stderr.
1101 .TP
1102 .BI .psbb \ filename
1103 Get the bounding box of a PostScript image
1104 .IR filename .
1105 This file must conform to Adobe's Document Structuring Conventions; the
1106 command looks for a
1107 .B %%BoundingBox
1108 comment to extract the bounding box values.
1109 After a successful call, the coordinates (in PostScript units) of the lower
1110 left and upper right corner can be found in the registers
1111 .BR \en[llx] ,
1112 .BR \en[lly] ,
1113 .BR \en[urx] ,
1114 and
1115 .BR \en[ury] ,
1116 respectively.
1117 If some error has occurred, the four registers are set to zero.
1118 .TP
1119 .BI .pso \ command
1120 This behaves like the
1121 .B so
1122 request except that input comes from the standard output of
1123 .IR command .
1124 .TP
1125 .B .ptr
1126 Print the names and positions of all traps (not including input line
1127 traps and diversion traps) on stderr. Empty slots in the page trap
1128 list are printed as well, because they can affect the priority of
1129 subsequently planted traps.
1130 .TP
1131 .BI .rchar\ c1\ c2\|.\|.\|.
1132 Remove the definitions of characters
1133 .IR c1 ,
1134 .IR c2 ,\|.\|.\|.
1135 This undoes the effect of a
1136 .B char
1137 request.
1138 .TP
1139 .B .rj
1140 .TQ
1141 .BI .rj\ n
1142 Right justify the next
1143 .I n
1144 input lines.
1145 Without an argument right justify the next input line.
1146 The number of lines to be right justified is available in the
1147 .B \en[.rj]
1148 register.
1149 This implicitly does
1150 .BR .ce\ 0 .
1151 The
1152 .B ce
1153 request implicitly does
1154 .BR .rj\ 0 .
1155 .TP
1156 .BI .rnn \ xx\ yy
1157 Rename number register
1158 .I xx
1159 to
1160 .IR yy .
1161 .TP
1162 .BI .shc\ c
1163 Set the soft hyphen character to
1164 .IR c .
1165 If
1166 .I c
1167 is omitted,
1168 the soft hyphen character will be set to the default
1169 .BR \e(hy .
1170 The soft hyphen character is the character which will be inserted
1171 when a word is hyphenated at a line break.
1172 If the soft hyphen character does not exist in the font of the character
1173 immediately preceding a potential break point,
1174 then the line will not be broken at that point.
1175 Neither definitions (specified with the
1176 .B char
1177 request)
1178 nor translations (specified with the
1179 .B tr
1180 request)
1181 are considered when finding the soft hyphen character.
1182 .TP
1183 .BI .shift\ n
1184 In a macro, shift the arguments by
1185 .I n
1186 positions:
1187 argument
1188 .I i
1189 becomes argument
1190 .IR i \- n ;
1191 arguments 1 to
1192 .I n
1193 will no longer be available.
1194 If
1195 .I n
1196 is missing,
1197 arguments will be shifted by 1.
1198 Shifting by negative amounts is currently undefined.
1199 .TP
1200 .BI .special\ s1\ s2\|.\|.\|.
1201 Fonts
1202 .IR s1 ,
1203 .IR s2 ,
1204 are special and will be searched for characters not in the
1205 current font.
1206 .TP
1207 .BI .sty\ n\ f
1208 Associate style
1209 .I f
1210 with font position
1211 .IR n .
1212 A font position can be associated either with a font or
1213 with a style.
1214 The current font is the index of a font position and so is also
1215 either a font or a style.
1216 When it is a style, the font that is actually used is the font the
1217 name of which is the concatenation of the name of the current family
1218 and the name of the current style.
1219 For example, if the current font is 1 and font position 1 is
1220 associated with style
1221 .B R
1222 and the current
1223 font family is
1224 .BR T ,
1225 then font
1226 .BR TR
1227 will be used.
1228 If the current font is not a style, then the current family is ignored.
1229 When the requests
1230 .BR cs ,
1231 .BR bd ,
1232 .BR tkf ,
1233 .BR uf ,
1234 or
1235 .B fspecial
1236 are applied to a style,
1237 then they will instead be applied to the member of the
1238 current family corresponding to that style.
1239 The default family can be set with the
1240 .B \-f
1241 option.
1242 The styles command in the
1243 .SM DESC
1244 file controls which font positions
1245 (if any) are initially associated with styles rather than fonts.
1246 .TP
1247 .BI .substring\ xx\ n1\ [ n2 ]
1248 Replace the string in register
1249 .I xx
1250 with the substring defined by the indices
1251 .I n1
1252 and
1253 .IR n2 .
1254 The first character in the string has index one.
1255 If
1256 .I n2
1257 is omitted, it is taken to be equal to the string's length. If the
1258 index value
1259 .I n1
1260 or
1261 .I n2
1262 is negative or zero, it will be counted from the end of the string,
1263 going backwards: The last character has index 0, the character before
1264 the last character has index -1, etc.
1265 .TP
1266 .BI .tkf\ f\ s1\ n1\ s2\ n2
1267 Enable track kerning for font
1268 .IR f .
1269 When the current font is
1270 .I f
1271 the width of every character will be increased by an amount
1272 between
1273 .I n1
1274 and
1275 .IR n2 ;
1276 when the current point size is less than or equal to
1277 .I s1
1278 the width will be increased by
1279 .IR n1 ;
1280 when it is greater than or equal to
1281 .I s2
1282 the width will be increased by
1283 .IR n2 ;
1284 when the point size is greater than or equal to
1285 .I s1
1286 and less than or equal to
1287 .I s2
1288 the increase in width is a linear function of the point size.
1289 .TP
1290 .BI .trf\ filename
1291 Transparently output the contents of file
1292 .IR filename .
1293 Each line is output as it would be were it preceded by
1294 .BR \e! ;
1295 however, the lines are not subject to copy-mode interpretation.
1296 If the file does not end with a newline, then a newline will
1297 be added.
1298 For example, you can define a macro
1299 .I x
1300 containing the contents of file
1301 .IR f ,
1302 using
1303 .RS
1304 .IP
1305 .BI .di\ x
1306 .br
1307 .BI .trf\ f
1308 .br
1309 .B .di
1310 .LP
1311 Unlike with the
1312 .B cf
1313 request,
1314 the file cannot contain characters such as
1315 .SM NUL
1316 that are not legal troff input characters.
1317 .RE
1318 .TP
1319 .B .trnt abcd
1320 This is the same as the
1321 .B tr
1322 request except that the translations do not apply to text that is
1323 transparently throughput into a diversion with
1324 .BR \e! .
1325 For example,
1326 .RS
1327 .LP
1328 .nf
1329 .ft B
1330 \&.tr ab
1331 \&.di x
1332 \e!.tm a
1333 \&.di
1334 \&.x
1335 .fi
1336 .ft
1337 .LP
1338 will print
1339 .BR b ;
1340 if
1341 .B trnt
1342 is used instead of
1343 .B tr
1344 it will print
1345 .BR a .
1346 .RE
1347 .TP
1348 .B .troff
1349 Make the
1350 .B n
1351 built-in condition false,
1352 and the
1353 .B t
1354 built-in condition true.
1355 This undoes the effect of the
1356 .B nroff
1357 request.
1358 .TP
1359 .BI .vpt\ n
1360 Enable vertical position traps if
1361 .I n
1362 is non-zero, disable them otherwise.
1363 Vertical position traps are traps set by the
1364 .B wh
1365 or
1366 .B dt
1367 requests.
1368 Traps set by the
1369 .B it
1370 request are not vertical position traps.
1371 The parameter that controls whether vertical position traps are enabled
1372 is global.
1373 Initially vertical position traps are enabled.
1374 .TP
1375 .BI .warn\ n
1376 Control warnings.
1377 .I n
1378 is the sum of the numbers associated with each warning that is to be enabled;
1379 all other warnings will be disabled.
1380 The number associated with each warning is listed in the `Warnings' section.
1381 For example,
1382 .B .warn 0
1383 will disable all warnings, and
1384 .B .warn 1
1385 will disable all warnings except that about missing characters.
1386 If
1387 .I n
1388 is not given,
1389 all warnings will be enabled.
1390 .TP
1391 .BI .while \ c\ anything
1392 While condition
1393 .I c
1394 is true, accept
1395 .I anything
1396 as input;
1397 .I c
1398 can be any condition acceptable to an
1399 .B if
1400 request;
1401 .I anything
1402 can comprise multiple lines if the first line starts with
1403 .B \e{
1404 and the last line ends with
1405 .BR \e} .
1406 See also the
1407 .B break
1408 and
1409 .B continue
1410 requests.
1411 .TP
1412 .BI .write\ stream\ anything
1413 Write
1414 .I anything
1415 to the stream named
1416 .IR stream .
1417 .I stream
1418 must previously have been the subject of an
1419 .B open
1420 request.
1421 .I anything
1422 is read in copy mode;
1423 a leading
1424 .B \(ts
1425 will be stripped.
1426 .SS Extended requests
1427 .TP
1428 .BI .cf\ filename
1429 When used in a diversion, this will embed in the diversion an object which,
1430 when reread, will cause the contents of
1431 .I filename
1432 to be transparently copied through to the output.
1433 In Unix troff, the
1434 contents of
1435 .I filename
1436 is immediately copied through to the output regardless of whether
1437 there is a current diversion; this behaviour is so anomalous that it
1438 must be considered a bug.
1439 .TP
1440 .BI .ev\ xx
1441 If
1442 .I xx
1443 is not a number, this will switch to a named environment called
1444 .IR xx .
1445 The environment should be popped with a matching
1446 .B ev
1447 request without any arguments, just as for numbered environments.
1448 There is no limit on the number of named environments; they will be
1449 created the first time that they are referenced.
1450 .TP
1451 .BI .fp\ n\ f1\ f2
1452 The
1453 .B fp
1454 request has an optional third argument.
1455 This argument gives the external name of the font,
1456 which is used for finding the font description file.
1457 The second argument gives the internal name of the font
1458 which is used to refer to the font in troff after it has been mounted.
1459 If there is no third argument then the internal name will be used
1460 as the external name.
1461 This feature allows you to use fonts with long names in compatibility mode.
1462 .TP
1463 .BI .ss\ m\ n
1464 When two arguments are given to the
1465 .B ss
1466 request, the second argument gives the
1467 .IR "sentence space size" .
1468 If the second argument is not given, the sentence space size
1469 will be the same as the word space size.
1470 Like the word space size, the sentence space is in units of
1471 one twelfth of the spacewidth parameter for the current font.
1472 Initially both the word space size and the sentence
1473 space size are 12.
1474 The sentence space size is used in two circumstances:
1475 if the end of a sentence occurs at the end of a line in fill mode, then
1476 both an inter-word space and a sentence space will be added;
1477 if two spaces follow the end of a sentence in the middle of a line,
1478 then the second space will be a sentence space.
1479 Note that the behaviour of Unix troff will be exactly
1480 that exhibited by GNU troff if a second argument is never given to the
1481 .B ss
1482 request.
1483 In GNU troff, as in Unix troff, you should always
1484 follow a sentence with either a newline or two spaces.
1485 .TP
1486 .BI .ta\ n1\ n2\|.\|.\|.nn \ T\ r1\ r2\|.\|.\|.\|rn
1487 Set tabs at positions
1488 .IR n1 ,
1489 .IR n2 ,\|.\|.\|.\|,
1490 .I nn
1491 and then set tabs at
1492 .IR nn + r1 ,
1493 .IR nn + r2 ,\|.\|.\|.\|.\|,
1494 .IR nn + rn
1495 and then at
1496 .IR nn + rn + r1 ,
1497 .IR nn + rn + r2 ,\|.\|.\|.\|,
1498 .IR nn + rn + rn ,
1499 and so on.
1500 For example,
1501 .RS
1502 .IP
1503 .B
1504 \&.ta T .5i
1505 .LP
1506 will set tabs every half an inch.
1507 .RE
1508 .SS New number registers
1509 The following read-only registers are available:
1510 .TP
1511 .B \en[.C]
1512 1 if compatibility mode is in effect, 0 otherwise.
1513 .TP
1514 .B \en[.cdp]
1515 The depth of the last character added to the current environment.
1516 It is positive if the character extends below the baseline.
1517 .TP
1518 .B \en[.ce]
1519 The number of lines remaining to be centered, as set by the
1520 .B ce
1521 request.
1522 .TP
1523 .B \en[.cht]
1524 The height of the last character added to the current environment.
1525 It is positive if the character extends above the baseline.
1526 .TP
1527 .B \en[.csk]
1528 The skew of the last character added to the current environment.
1529 The
1530 .I skew
1531 of a character is how far to the right of the center of a character
1532 the center of an accent over that character should be placed.
1533 .TP
1534 .B \en[.ev]
1535 The name or number of the current environment.
1536 This is a string-valued register.
1537 .TP
1538 .B \en[.fam]
1539 The current font family.
1540 This is a string-valued register.
1541 .TP
1542 .B \en[.fp]
1543 The number of the next free font position.
1544 .TP
1545 .B \en[.g]
1546 Always 1.
1547 Macros should use this to determine whether they are running
1548 under GNU troff.
1549 .TP
1550 .B \en[.hla]
1551 The current hyphenation language as set by the
1552 .B hla
1553 request.
1554 .TP
1555 .B \en[.hlc]
1556 The number of immediately preceding consecutive hyphenated lines.
1557 .TP
1558 .B \en[.hlm]
1559 The maximum allowed number of consecutive hyphenated lines, as set by the
1560 .B hlm
1561 request.
1562 .TP
1563 .B \en[.hy]
1564 The current hyphenation flags (as set by the
1565 .B hy
1566 request.)
1567 .TP
1568 .B \en[.hym]
1569 The current hyphenation margin (as set by the
1570 .B hym
1571 request.)
1572 .TP
1573 .B \en[.hys]
1574 The current hyphenation space (as set by the
1575 .B hys
1576 request.)
1577 .TP
1578 .B \en[.in]
1579 The indent that applies to the current output line.
1580 .TP
1581 .B \en[.kern]
1582 .B 1
1583 if pairwise kerning is enabled,
1584 .B 0
1585 otherwise.
1586 .TP
1587 .B \en[.lg]
1588 The current ligature mode (as set by the
1589 .B lg
1590 request.)
1591 .TP
1592 .B \en[.ll]
1593 The line length that applies to the current output line.
1594 .TP
1595 .B \en[.lt]
1596 The title length as set by the
1597 .B lt
1598 request.
1599 .TP
1600 .B \en[.ne]
1601 The amount of space that was needed in the last
1602 .B ne
1603 request that caused a trap to be sprung.
1604 Useful in conjunction with the
1605 .B \en[.trunc]
1606 register.
1607 .TP
1608 .B \en[.pn]
1609 The number of the next page:
1610 either the value set by a
1611 .B pn
1612 request, or the number of the current page plus 1.
1613 .TP
1614 .B \en[.ps]
1615 The current pointsize in scaled points.
1616 .TP
1617 .B \en[.psr]
1618 The last-requested pointsize in scaled points.
1619 .TP
1620 .B \en[.rj]
1621 The number of lines to be right-justified as set by the
1622 .B rj
1623 request.
1624 .TP
1625 .B \en[.sr]
1626 The last requested pointsize in points as a decimal fraction.
1627 This is a string-valued register.
1628 .TP
1629 .B \en[.tabs]
1630 A string representation of the current tab settings suitable for use as
1631 an argument to the
1632 .B ta
1633 request.
1634 .TP
1635 .B \en[.trunc]
1636 The amount of vertical space truncated by the most recently sprung
1637 vertical position trap, or,
1638 if the trap was sprung by a
1639 .B ne
1640 request,
1641 minus the amount of vertical motion produced by the
1642 .B ne
1643 request.
1644 In other words, at the point a trap is sprung, it represents the difference
1645 of what the vertical position would have been but for the trap,
1646 and what the vertical position actually is.
1647 Useful in conjunction with the
1648 .B \en[.ne]
1649 register.
1650 .TP
1651 .B \en[.ss]
1652 .TQ
1653 .B \en[.sss]
1654 These give the values of the parameters set by the
1655 first and second arguments of the
1656 .B ss
1657 request.
1658 .TP
1659 .B \en[.vpt]
1660 1 if vertical position traps are enabled, 0 otherwise.
1661 .TP
1662 .B \en[.warn]
1663 The sum of the numbers associated with each of the currently enabled
1664 warnings.
1665 The number associated with each warning is listed in the `Warnings'
1666 subsection.
1667 .TP
1668 .B \en(.x
1669 The major version number.
1670 For example, if the version number is
1671 .B 1.03
1672 then
1673 .B \en(.x
1674 will contain
1675 .BR 1 .
1676 .TP
1677 .B \en(.y
1678 The minor version number.
1679 For example, if the version number is
1680 .B 1.03
1681 then
1682 .B \en(.y
1683 will contain
1684 .BR 03 .
1685 .TP
1686 .B \en(.Y
1687 The revision number of groff.
1688 .TP
1689 .B \en[llx]
1690 .TQ
1691 .B \en[lly]
1692 .TQ
1693 .B \en[urx]
1694 .TQ
1695 .B \en[ury]
1696 These four registers are set by the
1697 .B \&.psbb
1698 request and contain the bounding box values (in PostScript units) of a given
1699 PostScript image.
1700 .LP
1701 The following registers are set by the
1702 .B \ew
1703 escape sequence:
1704 .TP
1705 .B \en[rst]
1706 .TQ
1707 .B \en[rsb]
1708 Like the
1709 .B st
1710 and
1711 .B sb
1712 registers, but takes account of the heights and depths of characters.
1713 .TP
1714 .B \en[ssc]
1715 The amount of horizontal space (possibly negative) that should
1716 be added to the last character before a subscript.
1717 .TP
1718 .B \en[skw]
1719 How far to right of the center of the last character
1720 in the
1721 .B \ew
1722 argument,
1723 the center of an accent from a roman font should be placed over that character.
1724 .LP
1725 The following read/write number registers are available:
1726 .TP
1727 .B \en[systat]
1728 The return value of the system() function executed by the last
1729 .B sy
1730 request.
1731 .TP
1732 .B \en[slimit]
1733 If greater than 0, the maximum number of objects on the input stack.
1734 If less than or equal to 0, there is no limit on the number of objects
1735 on the input stack. With no limit, recursion can continue until
1736 virtual memory is exhausted.
1737 .TP
1738 .B \en[year]
1739 The current year.
1740 Note that the traditional
1741 .B troff
1742 number register
1743 .B \en[yr]
1744 is the current year minus 1900.
1745 .SS Miscellaneous
1746 .LP
1747 Fonts not listed in the
1748 .SM DESC
1749 file are automatically mounted on the next available font position
1750 when they are referenced.
1751 If a font is to be mounted explicitly with the
1752 .B fp
1753 request on an unused font position,
1754 it should be mounted on the first unused font position,
1755 which can be found in the
1756 .B \en[.fp]
1757 register;
1758 although
1759 .B troff
1760 does not enforce this strictly,
1761 it will not allow a font to be mounted at a position whose number is much
1762 greater than that of any currently used position.
1763 .LP
1764 Interpolating a string does not hide existing macro arguments.
1765 Thus in a macro, a more efficient way of doing
1766 .IP
1767 .BI . xx\ \e\e$@
1768 .LP
1769 is
1770 .IP
1771 .BI \e\e*[ xx ]\e\e
1772 .LP
1773 If the font description file contains pairwise kerning information,
1774 characters from that font will be kerned.
1775 Kerning between two characters can be inhibited by placing a
1776 .B \e&
1777 between them.
1778 .LP
1779 In a string comparison in a condition,
1780 characters that appear at different input levels
1781 to the first delimiter character will not be recognised
1782 as the second or third delimiters.
1783 This applies also to the
1784 .B tl
1785 request.
1786 In a
1787 .B \ew
1788 escape sequence,
1789 a character that appears at a different input level to
1790 the starting delimiter character will not be recognised
1791 as the closing delimiter character.
1792 When decoding a macro argument that is delimited
1793 by double quotes, a character that appears at a different
1794 input level to the starting delimiter character will not
1795 be recognised as the closing delimiter character.
1796 The implementation of
1797 .B \e$@
1798 ensures that the double quotes surrounding an argument
1799 will appear the same input level, which will be different
1800 to the input level of the argument itself.
1801 In a long escape name
1802 .B ]
1803 will not be recognized as a closing delimiter except
1804 when it occurs at the same input level as the opening
1805 .BR ] .
1806 In compatibility mode, no attention is paid to the input-level.
1807 .LP
1808 There are some new types of condition:
1809 .TP
1810 .BI .if\ r xxx
1811 True if there is a number register named
1812 .IR xxx .
1813 .TP
1814 .BI .if\ d xxx
1815 True if there is a string, macro, diversion, or request named
1816 .IR xxx .
1817 .TP
1818 .BI .if\ c ch
1819 True if there is a character
1820 .IR ch
1821 available;
1822 .I ch
1823 is either an
1824 .SM ASCII
1825 character
1826 or a special character
1827 .BI \e( xx
1828 or
1829 .BI \e[ xxx ]\fR;
1830 the condition will also be true if
1831 .I ch
1832 has been defined by the
1833 .B char
1834 request.
1835 .SS Warnings
1836 The warnings that can be given by
1837 .B troff
1838 are divided into the following categories.
1839 The name associated with each warning is used by the
1840 .B \-w
1841 and
1842 .B \-W
1843 options;
1844 the number is used by the
1845 .B warn
1846 request, and by the
1847 .B .warn
1848 register.
1849 .nr x \w'\fBright-brace'+1n+\w'0000'u
1850 .ta \nxuR
1851 .TP \nxu+3n
1852 .BR char \t1
1853 Non-existent characters.
1854 This is enabled by default.
1855 .TP
1856 .BR number \t2
1857 Invalid numeric expressions.
1858 This is enabled by default.
1859 .TP
1860 .BR break \t4
1861 In fill mode, lines which could not be broken so that their length was
1862 less than the line length.
1863 This is enabled by default.
1864 .TP
1865 .BR delim \t8
1866 Missing or mismatched closing delimiters.
1867 .TP
1868 .BR el \t16
1869 Use of the
1870 .B el
1871 request with no matching
1872 .B ie
1873 request.
1874 .TP
1875 .BR scale \t32
1876 Meaningless scaling indicators.
1877 .TP
1878 .BR range \t64
1879 Out of range arguments.
1880 .TP
1881 .BR syntax \t128
1882 Dubious syntax in numeric expressions.
1883 .TP
1884 .BR di \t256
1885 Use of
1886 .B di
1887 or
1888 .B da
1889 without an argument when there is no current diversion.
1890 .TP
1891 .BR mac \t512
1892 Use of undefined strings, macros and diversions.
1893 When an undefined string, macro or diversion is used,
1894 that string is automatically defined as empty.
1895 So, in most cases, at most one warning will be given for
1896 each name.
1897 .TP
1898 .BR reg \t1024
1899 Use of undefined number registers.
1900 When an undefined number register is used,
1901 that register is automatically defined to have a value of 0.
1902 a definition is automatically made with a value of 0.
1903 So, in most cases, at most one warning will be given for
1904 use of a particular name.
1905 .TP
1906 .BR tab \t2048
1907 Inappropriate use of a tab character.
1908 Either use of a tab character where a number was expected,
1909 or use of tab character in an unquoted macro argument.
1910 .TP
1911 .BR right-brace \t4096
1912 Use of
1913 .B \e}
1914 where a number was expected.
1915 .TP
1916 .BR missing \t8192
1917 Requests that are missing non-optional arguments.
1918 .TP
1919 .BR input \t16384
1920 Illegal input characters.
1921 .TP
1922 .BR escape \t32768
1923 Unrecognized escape sequences.
1924 When an unrecognized escape sequence is encountered,
1925 the escape character is ignored.
1926 .TP
1927 .BR space \t65536
1928 Missing space between a request or macro and its argument.
1929 This warning will be given
1930 when an undefined name longer than two characters is encountered,
1931 and the first two characters of the name make a defined name.
1932 The request or macro will not be invoked.
1933 When this warning is given, no macro is automatically defined.
1934 This is enabled by default.
1935 This warning will never occur in compatibility mode.
1936 .TP
1937 .BR font \t131072
1938 Non-existent fonts.
1939 This is enabled by default.
1940 .TP
1941 .BR ig \t262144
1942 Illegal escapes in text ignored with the
1943 .B ig
1944 request.
1945 These are conditions that are errors when they do not occur
1946 in ignored text.
1947 .LP
1948 There are also names that can be used to refer to groups of warnings:
1949 .TP
1950 .B all
1951 All warnings except
1952 .BR di ,
1953 .B mac
1954 and
1955 .BR reg .
1956 It is intended that this covers all warnings
1957 that are useful with traditional macro packages.
1958 .TP
1959 .B w
1960 All warnings.
1961 .SS Incompatibilities
1962 .LP
1963 Long names cause some incompatibilities.
1964 Unix troff will interpret
1965 .IP
1966 .B
1967 \&.dsabcd
1968 .LP
1969 as defining a string
1970 .B ab
1971 with contents
1972 .BR cd .
1973 Normally, GNU troff will interpret this as a call of a macro named
1974 .BR dsabcd .
1975 Also Unix troff will interpret
1976 .B \e*[
1977 or
1978 .B \en[
1979 as references to a string or number register called
1980 .BR [ .
1981 In GNU troff, however, this will normally be interpreted as the start
1982 of a long name.
1983 In
1984 .I compatibility mode
1985 GNU troff will interpret these things in the traditional way.
1986 In compatibility mode, however, long names are not recognised.
1987 Compatibility mode can be turned on with the
1988 .B \-C
1989 command line option, and turned on or off with the
1990 .B cp
1991 request.
1992 The number register
1993 .B \en(.C
1994 is 1 if compatibility mode is on, 0 otherwise.
1995 .LP
1996 GNU troff
1997 does not allow the use of the escape sequences
1998 .BR \\e\e|\e^\e&\e}\e{\e (space) \e'\e`\e-\e_\e!\e%\ec
1999 in names of strings, macros, diversions, number registers,
2000 fonts or environments; Unix troff does.
2001 The
2002 .B \eA
2003 escape sequence may be helpful in avoiding use of these
2004 escape sequences in names.
2005 .LP
2006 Fractional pointsizes cause one noteworthy incompatibility.
2007 In Unix troff the
2008 .B ps
2009 request ignores scale indicators and so
2010 .IP
2011 .B .ps\ 10u
2012 .LP
2013 will set the pointsize to 10 points, whereas in
2014 GNU troff it will set the pointsize to 10 scaled points.
2015 .LP
2016 In GNU troff there is a fundamental difference between unformatted,
2017 input characters, and formatted, output characters.
2018 Everything that affects how an output character
2019 will be output is stored with the character; once an output
2020 character has been constructed it is unaffected by any subsequent
2021 requests that are executed, including
2022 .BR bd ,
2023 .BR cs ,
2024 .BR tkf ,
2025 .BR tr ,
2026 or
2027 .B fp
2028 requests.
2029 Normally output characters are constructed from input
2030 characters at the moment immediately before the character
2031 is added to the current output line.
2032 Macros, diversions and strings are all, in fact, the same type
2033 of object; they contain lists of input characters and output
2034 characters in any combination.
2035 An output character does not behave like an input character
2036 for the purposes of macro processing; it does not inherit any
2037 of the special properties that the input character from which it
2038 was constructed might have had.
2039 For example,
2040 .IP
2041 .nf
2042 .ft B
2043 \&.di x
2044 \e\e\e\e
2045 \&.br
2046 \&.di
2047 \&.x
2048 .ft
2049 .fi
2050 .LP
2051 will print
2052 .B \e\e
2053 in GNU troff;
2054 each pair of input
2055 .BR \e s
2056 is turned into one output
2057 .B \e
2058 and the resulting output
2059 .BR \e s
2060 are not interpreted as escape characters when they are reread.
2061 Unix troff would interpret them as escape characters
2062 when they were reread and would end up printing one
2063 .BR \e .
2064 The correct way to obtain a printable
2065 .B \e
2066 is to use the
2067 .B \ee
2068 escape sequence: this will always print a single instance of the
2069 current escape character, regardless of whether or not it is used in a
2070 diversion; it will also work in both GNU troff and Unix troff.
2071 If you wish for some reason to store in a diversion an escape
2072 sequence that will be interpreted when the diversion is reread,
2073 you can either use the traditional
2074 .B \e!
2075 transparent output facility, or, if this is unsuitable, the new
2076 .B \e?
2077 escape sequence.
2078 .SH ENVIRONMENT
2079 .TP
2080 .SM
2081 .B GROFF_TMAC_PATH
2082 A colon separated list of directories in which to search for
2083 macro files.
2084 .TP
2085 .SM
2086 .B GROFF_TYPESETTER
2087 Default device.
2088 .TP
2089 .SM
2090 .B GROFF_FONT_PATH
2091 A colon separated list of directories in which to search for the
2092 .BI dev name
2093 directory.
2094 .B troff
2095 will search in directories given in the
2096 .B \-F
2097 option before these, and in standard directories
2098 .RB ( @FONTPATH@ )
2099 after these.
2100 .SH FILES
2101 .Tp \w'@FONTDIR@/devname/DESC'u+3n
2102 .B @MACRODIR@/troffrc
2103 Initialization file
2104 .TP
2105 .BI @MACRODIR@/tmac. name
2106 Macro files
2107 .TP
2108 .BI @FONTDIR@/dev name /DESC
2109 Device description file for device
2110 .IR name .
2111 .TP
2112 .BI @FONTDIR@/dev name / F
2113 Font file for font
2114 .I F
2115 of device
2116 .IR name .
2117 .SH "SEE ALSO"
2118 .BR groff (@MAN1EXT@),
2119 .BR @g@tbl (@MAN1EXT@),
2120 .BR @g@pic (@MAN1EXT@),
2121 .BR @g@eqn (@MAN1EXT@),
2122 .BR grops (@MAN1EXT@),
2123 .BR grodvi (@MAN1EXT@),
2124 .BR grotty (@MAN1EXT@),
2125 .BR grohtml (@MAN1EXT@),
2126 .BR groff_font (@MAN5EXT@),
2127 .BR groff_out (@MAN5EXT@),
2128 .BR groff_char (@MAN7EXT@)