TODO

   1 ************************************************************************
   2 * Official mandoc TODO.
   3 * $Id: TODO,v 1.318 2021/09/10 12:48:19 schwarze Exp $
   4 ************************************************************************
   5
   6 Many issues are annotated for difficulty as follows:
   7
   8  - loc = locality of the issue
   9     *    single file issue, affects file only, or very few
  10     **   single module issue, affects several files of one module
  11     ***  cross-module issue, significantly impacts multiple modules
  12          and may require substantial changes to internal interfaces
  13  - exist = difficulty of the existing code in this area
  14     *    affected code is straightforward and easy to read and change
  15     **   affected code is somewhat complex, but once you understand
  16          the design, not particularly difficult to understand
  17     ***  affected code uses a special, exceptionally tricky design
  18  - algo = difficulty of the new algorithm to be written
  19     *    the required logic and code is straightforward
  20     **   the required logic is somewhat complex and needs a careful design
  21     ***  the required logic is exceptionally tricky,
  22          maybe an approach to solve that is not even known yet
  23  - size = the amount of code to be written or changed
  24     *    a small number of lines (at most 100, usually much less)
  25     **   a considerable amount of code (several dozen to a few hundred)
  26     ***  a large amount of code (many hundreds, maybe thousands)
  27  - imp = importance of the issue
  28     *    mostly for completeness
  29     **   would be nice to have
  30     ***  issue causes considerable inconvenience
  31
  32 Obviously, as the issues have not been solved yet, these annotations
  33 are mere guesses, and some may be wrong.
  34
  35 ************************************************************************
  36 * assertion failures
  37 ************************************************************************
  38
  39 - .if n .ce in the middle of .TS data
  40   afl case f1/id:000103,sig:06,src:009024+009105,op:splice,rep:2 (jes@)
  41   While roff_parseln() prevents .ce and similar requests in the middle
  42   of a tbl, the guard is no longer effective when the .ce is wrapped
  43   in a roff block, for example a conditional.  The resulting assertion
  44   has never been seen in any real-world manual page.
  45   This is too dangerous to fix before release because it requires
  46   reorganizing the very delicate internals of roff_parseln(),
  47   which risks causing more severe bugs.
  48   loc * exist *** algo *** size * imp *
  49
  50
  51 ************************************************************************
  52 * bugs: invalid output
  53 ************************************************************************
  54
  55 - wrong number of layout columns in tbl(7) code generated by -T man
  56   https://savannah.gnu.org/bugs/?57720
  57   The reason likely is that tbl(7) does not support the -Bl -column
  58   feature of not explicitly specifying the last table column.
  59   loc **  exist *  algo **  size *  imp ***
  60
  61 - eqn(7) delimiters cause conditional lines to misbehave
  62   nabijaczleweli 8 Sep 2021 15:24:48 +0200
  63   loc *  exist ***  algo ***  size *  imp *
  64
  65 - roff.c, roff_expand() should not remove blanks before comments
  66   to Oliver Corff, Sep 7, 2021
  67   loc *  exist *  algo *  size *  imp *
  68   but watch out for regressions in the high-level parsers
  69   maybe it should not even remove comments? - consider T{\"
  70
  71
  72 ************************************************************************
  73 * missing features
  74 ************************************************************************
  75
  76 --- missing roff features ----------------------------------------------
  77
  78 - .ad (adjust margins)
  79   .ad l -- adjust left margin only (flush left)
  80   .ad r -- adjust right margin only (flush right)
  81   .ad c -- center text on line
  82   .ad b -- adjust both margins (alias: .ad n)
  83   .na   -- temporarily disable adjustment without changing the mode
  84   .ad   -- re-enable adjustment without changing the mode
  85   Adjustment mode is ignored while in no-fill mode (.nf).
  86   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
  87
  88 - .fc (field control)
  89   found by naddy@ in xloadimage(1)
  90   loc **  exist ***  algo *  size *  imp *
  91
  92 - .ns (no-space mode) occurs in xine-config(1)
  93   when implementing this, also let .TH set it
  94   reported by brad@  Sat, 15 Jan 2011 15:45:23 -0500
  95   loc ***  exist ***  algo ***  size **  imp *
  96
  97 - \w'' improve width measurements
  98   would not be very useful without an expression parser, see below
  99   needed for Tcl_NewStringObj(3) via wiz@  Wed, 5 Mar 2014 22:27:43 +0100
 100   loc **  exist ***  algo ***  size *  imp ***
 101
 102 - .als only works for macros in mandoc, not for user-defined strings.
 103   Also, the "val" field in struct roffkv would have to be replaced
 104   with a pointer to a reference-counted wrapper, and an alias
 105   would have to point to the same wrapper as the original.
 106   .als to undefined does nothing; the alias is not created.
 107   .rm'ing the original leaves the alias to point to the old value.
 108   .de .als .de changes both, but
 109   .de .als .rm .de only changes the new value, not the alias.
 110   Found in groffer(1) version 1.19
 111   Jan Stary 20 Apr 2019 20:16:54 +0200
 112   loc *  exist **  algo **  size **  imp *
 113
 114 - roff string condition comparisons fail when vars contain quotes:
 115   .ds s '
 116   .if '\*s'' \&...
 117   hard to fix because of the basic architecture (string replacement
 118   happens before roff(7) syntax parsing)
 119   Found in groffer(1) version 1.19
 120   Jan Stary 20 Apr 2019 20:16:54 +0200
 121   loc *  exist ***  algo ***  size **  imp *
 122
 123 - mandoc replaces all ASCII control characters except tab and line feed
 124   with '?' during input.  It would be better to replace them with
 125   Unicode escapes in preconv_encode() or somewhere in the vicinity,
 126   such that the already existing better replacement strings show
 127   up in the output.  Emulating groff is not desirable: groff replaces
 128   0x00, 0x0b, and 0x0d to 0x1f with the empty string (bad because
 129   that's easy to overlook for the document author), 0x01 with '.'
 130   (very confusing), and passes through 0x02 to 0x08, 0x0c, and 0x7f
 131   raw (bad because that is insecure output).  Remember that 0x07 may
 132   need special handling because it is sometimes used for certain
 133   delimiters, so it may need handling *after* roff.c rather than before.
 134   reminded by John Gardner 16 Jun 2020 14:26:28 +1000
 135   Actually, more ASCII control characters than just 0x07 may need
 136   later handling because they can for example be used in macro names.
 137   So they may need handling after roff(7) processing.
 138   pointed out by John Gardner 23 Jun 2020 18:28:08 +1000
 139   more info from John Gardner 29 Jun 2020 19:54:04 +1000
 140   loc **  exist **  algo **  size **  imp *
 141
 142 - many missing features used in old groff_char(7),
 143   some can possibly be supported
 144   kamil at netbsd 12 Nov 2020 17:27:09 +0100 + reply
 145
 146 - \s with arbitrary arg delimiters as already supported for other escapes
 147   found following jmc@'s mail 28 Apr 2021 18:31:41 +0100
 148   loc *  exist *  algo *  size *  imp *
 149
 150 --- missing mdoc features ----------------------------------------------
 151
 152 - .Sh and .Ss should be parsed and partially callable, see groff_mdoc(7)
 153   reed at reedmedia dot net Sat, 21 Dec 2019 17:13:07 -0600
 154   loc **  exist **  algo **  size **  imp *
 155
 156 - .Bl -column .Xo support is missing
 157   ultimate goal:
 158   restore .Xr and .Dv to
 159   lib/libc/compat-43/sigvec.3
 160   lib/libc/gen/signal.3
 161   lib/libc/sys/sigaction.2
 162   loc *  exist ***  algo ***  size *  imp **
 163
 164 - edge case: decide how to deal with blk_full bad nesting, e.g.
 165   .Sh .Nm .Bk .Nm .Ek .Sh found by jmc@ in ssh-keygen(1)
 166   from jmc@  Wed, 14 Jul 2010 18:10:32 +0100
 167   loc *  exist ***  algo ***  size **  imp **
 168
 169 - .Bd -filled should not be the same as .Bd -ragged, but align both
 170   the left and right margin.  In groff, it is implemented in terms
 171   of .ad b, which we don't have either.  Found in cksum(1).
 172   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
 173
 174 - implement blank `Bl -column', such as
 175   .Bl -column
 176   .It foo Ta bar
 177   .El
 178   loc *  exist ***  algo ***  size *  imp *
 179
 180 - explicitly disallow nested `Bl -column', which would clobber internal
 181   flags defined for struct mdoc_macro
 182   loc *  exist *  algo *  size *  imp **
 183
 184 - In .Bl -column .It, the end of the line probably has to be regarded
 185   as an implicit .Ta, if there could be one, see the following mildly
 186   ugly code from login.conf(5):
 187     .Bl -column minpasswordlen program xetcxmotd
 188     .It path Ta path Ta value of Dv _PATH_DEFPATH
 189     .br
 190     Default search path.
 191   reported by Michal Mazurek <akfaew at jasminek dot net>
 192   via jmc@ Thu, 7 Apr 2011 16:00:53 +0059
 193   loc *  exist ***  algo **  size *  imp **
 194
 195 - inside `.Bl -column' phrases, punctuation is handled like normal
 196   text, e.g. `.Bl -column .It Fl x . Ta ...' should give "-x -."
 197
 198 - inside `.Bl -column' phrases, TERMP_IGNDELIM handling by `Pf'
 199   is not safe, e.g. `.Bl -column .It Pf a b .' gives "ab."
 200   but should give "ab ."
 201
 202 - prohibit `Nm' from having non-text HEAD children
 203   (e.g., NetBSD mDNSShared/dns-sd.1)
 204   (mdoc_html.c and mdoc_term.c `Nm' handlers can be slightly simplified)
 205
 206 - support translated section names
 207   e.g. x11/scrotwm scrotwm_es.1:21:2: error: NAME section must be first
 208   that one uses NOMBRE because it is spanish...
 209   deraadt tends to think that section-dependent macro behaviour
 210   is a bad idea in the first place, so this may be irrelevant
 211   loc **  exist **  algo **  size *  imp **
 212
 213 - When there is free text in the SYNOPSIS and that free text contains
 214   the .Nm macro, groff somehow understands to treat the .Nm as an in-line
 215   macro, while mandoc treats it as a block macro and breaks the line.
 216   No idea how the logic for distinguishing in-line and block instances
 217   should be, needs investigation.
 218   uqs@  Thu, 2 Jun 2011 11:03:51 +0200
 219   uqs@  Thu, 2 Jun 2011 11:33:35 +0200
 220   loc *  exist **  algo ***  size *  imp **
 221
 222 --- missing man features -----------------------------------------------
 223
 224 - MANWIDTH
 225   Markus Waldeck <waldeck at gmx dot de> 9 Jun 2015 05:49:56 +0200
 226   Laura Morales <lauretas at mail dot com> 26 Apr 2018 08:15:55 +0200
 227   Kamil Rytarowski <kamil at netbsd> 13 Nov 2020 00:19:36 +0100
 228   patch from Kamil 13 Nov 2020 22:37:07 +0100
 229   loc *  exist *  algo *  size *  imp *
 230
 231 - groff_www(7) .MTO and .URL
 232   These macros were used by the GNU grep(1) man page.
 233   The groff_www(7) manual page itself uses them, too.
 234   We should probably *not* add them to mandoc.
 235   Just mentioning this here to keep track of the abuse.
 236   Laura Morales <lauretas at mail dot com> 20 Apr 2018 07:33:02 +0200
 237   loc **  exist *  algo *  size **  imp *
 238
 239 --- missing tbl features -----------------------------------------------
 240
 241 - vertical centering in cells vertically spanned with ^
 242   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
 243   loc *  exist ***  algo ***  size **  imp *
 244
 245 - support mdoc(7) and man(7) macros inside tbl(7) code;
 246   probably requires the parser reorg and letting tbl(7)
 247   use roff_node such that macro sets can mix;
 248   informed by bapt@ that FreeBSD needs this: 3 Jan 2015 23:32:23 +0100
 249   loc ***  exist **  algo ***  size **  imp ***
 250
 251 - look at the POSIX manuals in the books/man-pages-posix port,
 252   they use some unsupported tbl(7) features, mostly macros in tbl(7).
 253   loc *  exist **  algo **  size **  imp ***
 254
 255 - look what Joerg Schilling manual pages use
 256   Thu, 19 Mar 2015 18:31:48 +0100
 257
 258 --- missing eqn features -----------------------------------------------
 259
 260 - In a matrix, break the output line after each matrix line.
 261   Found in the discussion at CDBUG 2015.  Suggested by Avi Weinstock.
 262   This may not be the ideal solution after all: eqn(7) matrices
 263   are lists of columns, so Avi's proposal would show each *column*
 264   on its own *line*, which is likely to cause confusion.
 265   A better solution, but much harder to implement, would be to
 266   actually show the coordinates of column vectors on different
 267   terminal output lines, using the clumnated output facilities
 268   developed for .Bl -tag, .Bl -column, and also used for tbl(7).
 269   loc *  exist *  algo **  size **  imp **
 270
 271 - The "size" keyword is parsed, but ignored by the formatter.
 272   loc *  exist *  algo *  size *  imp *
 273
 274 - The spacing characters `~', `^', and tab are currently ignored,
 275   see User's Guide (Second Edition) page 2 section 4.
 276   loc *  exist *  algo **  size *  imp **
 277
 278 - Mark and lineup are parsed and ignored,
 279   see User's Guide (Second Edition) page 5 section 15.
 280   loc **  exist **  algo **  size **  imp **
 281
 282 - GNU eqn converts some operators to special characters, for example,
 283   input HYPHEN-MINUS becomes output \(mi, unless it is part of a
 284   quoted word.  mandoc(1) only does this when the operator is
 285   surrounded by blanks, not when it is part of an unquoted word.
 286   Also, check whether there are more such cases (e.g., +?).
 287   reported by bentley@  20 Jun 2017 02:04:29 -0600
 288   loc *  exist **  algo **  size *  imp *
 289
 290 - Primes, opprime, and '
 291   bentley@  Thu, 13 Jul 2017 23:14:20 -0600
 292
 293 --- missing misc features ----------------------------------------------
 294
 295 - let makewhatis(8) follow symbolic links to dirs below READ_ALLOWED_PATH
 296   this may be feasible using fts_set(FTS_FOLLOW)
 297   mail to sternenseemann 19 Aug 2021 19:11:50 +0200
 298   loc *  exist **  algo **  size *  imp **
 299
 300 - -T man does not handle eqn(7) and tbl(7)
 301   Stephen Gregoratto 16 Feb 2020 01:28:07 +1100
 302   also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=901636
 303   loc **  exist **  algo **  size ***  imp **
 304
 305 - man -ks 1,8 route; kn@ Jul 13, 2018 orally
 306
 307 - italic correction (\/) in PostScript mode
 308   Werner LEMBERG on groff at gnu dot org  Sun, 10 Nov 2013 12:47:46
 309   loc **  exist **  algo *  size *  imp *
 310
 311 - change the default PAGER to more -Es and use the pager
 312   even for apropos title line output; req by bapt@
 313   loc *  exist *  algo *  size *  imp ***
 314
 315 - clean up escape sequence handling, creating three classes:
 316   (1) fully implemented, or parsed and ignored without loss of content
 317   (2) unimplemented, potentially causing loss of content
 318       or serious mangling of formatting (e.g. \n) -> ERROR
 319       see textproc/mgdiff(1) for nice examples
 320   (3) undefined, just output the character -> perhaps WARNING
 321   loc ***  exist **  algo **  size **  imp *** (parser reorg helps)
 322
 323 - kettenis wants base roff, ms, and me  Fri, 1 Jan 2010 22:13:15 +0100 (CET)
 324   loc **  exist **  algo **  size ***  imp *
 325
 326 --- compatibility checks -----------------------------------------------
 327
 328 - is .Bk implemented correctly in modern groff?
 329   sobrado@  Tue, 19 Apr 2011 22:12:55 +0200
 330
 331 - compare output to Heirloom roff, Solaris roff, and
 332   http://repo.or.cz/w/neatroff.git  http://litcave.rudi.ir/
 333
 334 - look at AT&T DWB http://www2.research.att.com/sw/download
 335   Carsten Kunze <carsten dot kunze at arcor dot de> has patches
 336   Mon, 4 Aug 2014 17:01:28 +0200
 337   ported version: https://github.com/n-t-roff/DWB3.3
 338   Carsten Kunze  Wed, 22 Apr 2015 11:21:43 +0200
 339
 340 - look at pages generated from reStructeredText, e.g. devel/mercurial hg(1)
 341   These are a weird mixture of man(7) and custom autogenerated low-level
 342   roff stuff.  Figure out to what extent we can cope.
 343   For details, see http://docutils.sourceforge.net/rst.html
 344   noted by stsp@  Sat, 24 Apr 2010 09:17:55 +0200
 345   reminded by nicm@  Mon, 3 May 2010 09:52:41 +0100
 346
 347 - look at pages generated from ronn(1) github.com/rtomayko/ronn
 348   (based on markdown)
 349
 350 - look at pages generated from Texinfo source by yat2m, e.g. security/gnupg
 351   First impression is not that bad.
 352
 353 - look at pages generated by pandoc; see
 354   https://github.com/jgm/pandoc/blob/master/src/Text/Pandoc/Writers/Man.hs
 355   porting planned by kili@  Thu, 19 Jun 2014 19:46:28 +0200
 356
 357 - check compatibility with Plan9:
 358   http://swtch.com/usr/local/plan9/tmac/tmac.an
 359   http://swtch.com/plan9port/man/man7/man.html
 360   "Anthony J. Bentley" <anthonyjbentley@gmail.com> 28 Dec 2010 21:58:40 -0700
 361
 362 - check compatibility with COHERENT troff:
 363   http://www.nesssoftware.com/home/mwc/source.php
 364
 365 - check compatibility with the man(7) formatter
 366   https://raw.githubusercontent.com/rofl0r/hardcore-utils/master/man.c
 367
 368 - check compatibility with
 369   http://ikiwiki.info/plugins/contrib/mandoc/
 370   https://github.com/schmonz/ikiwiki/compare/mandoc
 371   Amitai Schlair  Mon, 19 May 2014 14:05:53 -0400
 372
 373 - check compatibility with
 374   https://git.sr.ht/~sircmpwn/scdoc
 375
 376 - check features of the Slackware man.conf(5) format
 377   Carsten Kunze  Wed, 11 Mar 2015 17:57:24 +0100
 378
 379 - look at http://www.snake.net/software/troffcvt/  (troff to HTML)
 380   mentioned by Oliver Corff  22 Jan 2021 01:36:49 +0100
 381
 382
 383 ************************************************************************
 384 * formatting issues: ugly output
 385 ************************************************************************
 386
 387 - revisit empty in-line macros
 388   look at the difference between "Em x Em ." and "Sq x Em ."
 389   Carsten Kunze  Fri, 12 Dec 2014 00:15:41 +0100
 390   loc *** exist *** algo *** size * imp **
 391
 392 - a column list with blank `Ta' cells triggers a spurious
 393   start-with-whitespace printing of a newline
 394
 395 - In .Bl -column, .It a<tab>"b<tab>c"
 396   shows the quotes in groff, but not in mandoc
 397   loc * exist *** algo ** size * imp **
 398
 399 - In .Bl -column,
 400   .It Em Authentication<tab>Key Length
 401   ought to render "Key Length" with emphasis, too,
 402   see OpenBSD iked.conf(5).
 403   reported again Nicolas Joly via wiz@ Wed, 12 Oct 2011 00:20:00 +0200
 404   loc *  exist ***  algo ***  size **  imp ***
 405
 406 - empty phrases in .Bl column produce too few blanks
 407   try e.g. .Bl -column It Ta Ta
 408   reported by millert Fri, 02 Apr 2010 16:13:46 -0400
 409   loc *  exist ***  algo ***  size *  imp **
 410
 411 - .%T can have trailing punctuation.  Currently, it puts the trailing
 412   punctuation into a trailing MDOC_TEXT element inside its own scope.
 413   That element should rather be outside its scope, such that the
 414   punctuation does not get underlines.  This is not trivial to
 415   implement because .%T then needs some features of in_line_eoln() -
 416   slurp all arguments into one single text element - and one feature
 417   of in_line() - put trailing punctuation out of scope.
 418   Found in mount_nfs(8) and exports(5), search for "Appendix".
 419   loc **  exist **  algo ***  size *  imp **
 420
 421 - Trailing punctuation after .%T triggers EOS spacing, at least
 422   outside .Rs (eek!).  Simply setting ARGSFL_DELIM for .%T is not
 423   the right solution, it sends mandoc into an endless loop.
 424   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 425   loc *  exist **  algo **  size *  imp **
 426
 427 - global variables in the SYNOPSIS of section 3 pages
 428   .Vt vs .Vt/.Va vs .Ft/.Va vs .Ft/.Fa ...
 429   from kristaps@  Tue, 08 Jun 2010 11:13:32 +0200
 430
 431 - implicit whitespace around inline equations
 432   example code:  where '$times$' denotes matrix multiplication
 433   must not have an HTML line break, nor a blank, before <math>
 434   partial solution: html.c {"math", HTML_NLINSIDE | HTML_INDENT},
 435   bentley@  Thu, 13 Jul 2017 19:00:59 -0600
 436
 437 - in enclosures, mandoc sometimes fancies a bogus end of sentence
 438   reminded by jmc@  Thu, 23 Sep 2010 18:13:39 +0059
 439   loc *  exist **  algo ***  size *  imp ***
 440
 441 - a line starting with "\fB something" counts as starting with whitespace
 442   and triggers a line break; found in audio/normalize-mp3(1)
 443   This will become easier once escape sequences are represented
 444   by syntax tree nodes.
 445   loc **  exist *  algo **  size *  imp **
 446
 447 - formatting /usr/local/man/man1/latex2man.1 with groff and mandoc
 448   reveals lots of bugs both in groff and mandoc...
 449   reported by bentley@  Wed, 22 May 2013 23:49:30 -0600
 450
 451 --- PostScript and PDF issues ------------------------------------------
 452
 453 - PDF output doesn't use a monospaced font for .Bd -literal
 454   Example: "mandoc -Tpdf afterboot.8 > output.pdf && pdfviewer output.pdf".
 455   Search the text "Routing tables".
 456   Also check what PostScript mode does when fixing this.
 457   reported by juanfra@ Wed, 04 Jun 2014 21:44:58 +0200
 458   instructions from juanfra@  Wed, 11 Jun 2014 02:21:01 +0200
 459     add a new <</Type /Font>> block to the PDF files with /BaseFont /Courier
 460     and change the /Name from /F0 to the new font (/F5 (?)).
 461   re-reported by tb@ Mon, 16 Mar 2015 16:47:21 +0100
 462   loc **  exist **  algo **  size *  imp **
 463
 464 --- HTML issues --------------------------------------------------------
 465
 466 - make the HTML scaffolding customozable with -O skip=...
 467   mail to Oliver Corff  3 Jun 2021 17:28:02 +0200
 468   more feedback from Oliver  3 Jun 2021 18:27:56 +0200
 469   more feedback from Oliver  3 Jun 2021 23:37:18 +0200
 470
 471 - .Bd -unfilled should not use monospaced font
 472   anton@  4 Mar 2021 08:19:35 +0100
 473   loc **  exist *  algo *  size *  imp **
 474
 475 - HTML formatting of .nf should avoid <br/>
 476   and not close and re-open <pre> on .P
 477   my mail to ports@ 27 Jun 2021 16:09:20 +0200
 478   loc **  exist **  algo *  size *  imp **
 479
 480 - get rid of the last handful of style= attributes such that
 481   Content-Security-Policy: can be enabled without unsafe-inline
 482   suggested by bentley@  Nov 10, 2019 at 06:02:49AM -0700
 483   loc *  exist *  algo *  size *  imp **
 484
 485 - .Bf at the beginning of a paragraph inserts a bogus 1ex horizontal
 486   space, see for example random(3).  Introduced in
 487   http://mdocml.bsd.lv/cgi-bin/cvsweb/mdoc_html.c.diff?r1=1.91&r2=1.92
 488   reported by deraadt@ Mon, 28 Sep 2015 20:14:13 -0600 (MDT)
 489   loc **  exist **  algo **  size *  imp *
 490
 491 - jsg on icb, Nov 3, 2014:
 492   try to guess Xr in man(7) for hyperlinking
 493   and render them with <a class="Xr" href=...>
 494   https://github.com/Debian/debiman/issues/15
 495   loc *  exist *  algo **  size **  imp **
 496
 497 - space characters can end up in href= attributes, for example coming
 498   from the first .Xr argument (where they make no sense, but still);
 499   does this affect other characters, other source macros...?
 500   Jackson Pauls  29 Aug 2017 16:56:27 +0100
 501
 502 - The tables used to render the three-part page headers actually force
 503   the width of the <body> to the max-width given for <html>.
 504   Not yet sure how to fix that...
 505   Observed by an Anonymous Coward on undeadly.org:
 506   http://undeadly.org/cgi?action=article&sid=20140925064244&pid=1
 507   loc *  exist *  algo **  size *  imp ***
 508
 509 - generate <img> tags in HTML
 510   idea from florian@  Tue, 7 Apr 2015 00:26:28 +0000
 511   may be possible to implement with .Lk img://something.png alt_text
 512
 513 - check https://github.com/trentm/mdocml
 514
 515 ************************************************************************
 516 * formatting issues: gratuitous differences
 517 ************************************************************************
 518
 519 - .Fn reopens a new scope after punctuation in mandoc,
 520   but closes its scope for good in groff.
 521   Do we want to change mandoc or groff?
 522   Steffen Nurpmeso  Sat, 08 Nov 2014 13:34:59 +0100
 523   loc *  exist **  algo **  size *  imp **
 524
 525 - In .Bl -enum -width 0n, groff continues one the same line after
 526   the number, mandoc breaks the line.
 527   mail to kristaps@  Mon, 20 Jul 2009 02:21:39 +0200
 528   loc *  exist **  algo **  size *  imp **
 529
 530 - .Pp between two .It in .Bl -column should produce one,
 531   not two blank lines, see e.g. login.conf(5).
 532   reported by jmc@  Sun, 17 Apr 2011 14:04:58 +0059
 533   reported again by sthen@  Wed, 18 Jan 2012 02:09:39 +0000 (UTC)
 534   loc *  exist ***  algo **  size *  imp **
 535
 536 - If the *first* line after .It is .Pp, break the line right after
 537   the tag, do not pad with space characters before breaking.
 538   See the description of the a, c, and i commands in sed(1).
 539   loc *  exist **  algo **  size *  imp **
 540
 541 - If the first line after .It is .D1, do not assert a blank line
 542   in between, see for example tmux(1).
 543   reported by nicm@  13 Jan 2011 00:18:57 +0000
 544   loc *  exist **  algo **  size *  imp **
 545
 546 - Trailing punctuation after .It should trigger EOS spacing.
 547   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 548   Probably, this should be fixed somewhere in termp_it_pre(), not sure.
 549   loc *  exist **  algo **  size *  imp **
 550
 551 - When the -width string contains macros, the macros must be rendered
 552   before measuring the width, for example
 553     .Bl -tag -width ".Dv message"
 554   in magic(5), located in src/usr.bin/file, is the same
 555   as -width 7n, not -width 11n.
 556   The same applies to .Bl -column column widths;
 557   reported again by Nicolas Joly Thu, 1 Mar 2012 13:41:26 +0100 via wiz@ 5 Mar
 558   reported again by Franco Fichtner Fri, 27 Sep 2013 21:02:28 +0200
 559   reported again by Bruce Evans Fri, 17 Feb 2017 21:22:44 +0100 via bapt@
 560   loc ***  exist ***  algo ***  size **  imp ***
 561   An easy partial fix would be to just skip the first word if it starts
 562   with a dot, including any following white space, when measuring.
 563   loc *  exist *  algo *  size *  imp ***
 564
 565 - The \& zero-width character counts as output.
 566   That is, when it is alone on a line between two .Pp,
 567   we want three blank lines, not two as in mandoc.
 568   loc **  exist **  algo **  size *  imp **
 569
 570 - Sequences of multiple man(7) paragraphs (.PP, .IP) interspersed
 571   with .ps and .nf/.fi produce execessive blank lines, see libJudy
 572   and graphics/dcmtk.  The parser reorg may help with this.
 573
 574 - trailing whitespace must be ignored even when followed by a font escape,
 575   see for example
 576     makes
 577     \fBdig \fR
 578     operate in batch mode
 579   in dig(1).
 580   loc **  exist **  algo **  size *  imp **
 581
 582 ************************************************************************
 583 * warning issues
 584 ************************************************************************
 585
 586 - shorten/simplify error messages for usage errors
 587   To: deraadt@ 25 Oct 2020 23:37:01 +0100
 588   loc **  exist *  algo *  size **  imp ***
 589
 590 - warn about duplicate .Sh/.Ss heads
 591   gre(4): Rename duplicate sections 20 Apr 2018 15:27:33 +0200
 592   loc *  exist *  algo *  size *  imp **
 593
 594 - style message about macros inside .Bd -literal and .Dl, in particular
 595   font changing macros like .Cm, .Ar, .Fa (from the mdoclint TODO)
 596
 597 - style message about mismatches between the section number in the
 598   file name (if it is known) and the section number in .Dt
 599   (from the mdoclint TODO)
 600
 601 - style message about NULL without .Dv (from the mdoclint TODO)
 602
 603 - style message about error constants without .Er (from the mdoclint TODO)
 604
 605 - warn when .Sh or .Ss contain other macros
 606   Steffen Nurpmeso, savannah.gnu.org/bugs/index.php?45034
 607   loc *  exist *  algo *  size *  imp **
 608
 609 - style message about violations of the convention
 610   .An name Aq Mt localpart@domain in AUTHORS (from the mdoclint TODO)
 611
 612 - warn about attempts to call non-callable macros
 613   Steffen Nurpmeso  Tue, 11 Nov 2014 22:55:16 +0100
 614   Note that formatting is inconsistent in groff.
 615   .Fn Po prints "Po()", .Ar Sh prints "file ..." and no "Sh".
 616   Relatively hard because the relevant code is scattered
 617   all over mdoc_macro.c and all subtly different.
 618   loc **  exist **  algo **  size **  imp **
 619
 620 - warn about punctuation - e.g. ',' and ';' - at the beginning
 621   of a text line, if it is likely intended to follow the preceding
 622   output without intervening whitespace, in particular after a
 623   macro line (from the mdoclint TODO)
 624
 625 - report double .TH in man(7) as an ERROR and let the first win
 626   kristaps@  28 Mar 2021 13:30:41 +0200
 627   loc *  exist *  algo *  size *  imp *
 628
 629 - makewhatis -p complains about language subdirectories:
 630   /usr/local/man//ru: Unknown directory part
 631
 632
 633 ************************************************************************
 634 * documentation issues
 635 ************************************************************************
 636
 637 - mark macros as: page structure domain, manual domain, general text domain
 638   is this useful?
 639
 640 - mention /usr/share/misc/mdoc.template in mdoc(7)?
 641
 642 - Is all the content from http://www.std.com/obi/BSD/doc/usd/28.tbl/tbl
 643   covered in tbl(7)?
 644
 645 ************************************************************************
 646 * performance issues
 647 ************************************************************************
 648
 649 - the PDF file is HUGE: this can be reduced by using relative offsets
 650
 651 ************************************************************************
 652 * structural issues
 653 ************************************************************************
 654
 655 - POSIX says in the documentation of sysconf(3) that PATH_MAX
 656   is allowed to be so large that it is a bad idea to use it
 657   for sizing static buffers.  So use dynamic buffers throughout.
 658   See the file test-PATH_MAX.c for details.
 659   Found by Aaron M. Ucko in the GNU Hurd via Bdale Garbee,
 660   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=829624
 661
 662 - Is it possible to further simplify ENDBODY_SPACE?
 663
 664 - Find better ways to prevent endless loops
 665   in roff(7) macro and string expansion.
 666
 667 - make buffers for parsing functions const
 668   christos@ via wiz@  Fri, 18 Dec 2015 17:10:01 +0100
 669
 670 - struct mparse refactoring
 671   Steffen Nurpmeso  Thu, 04 Sep 2014 12:50:00 +0200
 672
 673 ************************************************************************
 674 * CGI issues
 675 ************************************************************************
 676
 677  - Inspect httpd(8) logs on man.openbsd.org and consider
 678    whether logging can be improved, where bad syntax comes from,
 679    and what needs to be done to get rid of COMPAT_OLDURI.
 680  - Enable HTTP compression by detecting gzip encoding and filtering
 681    output through libz.
 682  - Privilege separation (see OpenSSH).
 683  - Enable caching support via HTTP 304 and If-Modified-Since.
 684
 685 ************************************************************************
 686 * to improve in the groff_mdoc(7) macros
 687 ************************************************************************
 688
 689 - delete OS release verification from .Dx, .Fx, .Nx, .Ox etc.
 690   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629161
 691   also Branden Robinson 18 Dec 2019 00:59:52 +1100
 692
 693 - Can the distinction between .Vt and .Va be made stricter,
 694   recommending .Vt extern char * Ns Va optarg ; ?
 695   What about the block macro properties of .Vt in the SYNOPSIS?
 696   zeurkous 25 Dec 2019 08:48:36 +0100
 697
 698 - .Cd # arch1, arch2 in section 4 pages:
 699   find better way to indicate multiple architectures, maybe:
 700   allow .Dt vgafb 4 "macppc sparc64"
 701   already shown as "Device Drivers Manual (macppc sparc64)"
 702   for apropos, make that "vgafb(4) - macppc # sparc64" instead of "- all"
 703   groff can be made to show multiple arches, too, but it is
 704   tedious to do the string parsing in roff code...
 705   jmc@ 23 Apr 2018 07:24:52 +0100 [man for vgafb(4)...]
 706   loc **  exist **  algo *  size *  imp ***
 707
 708 - use uname(1) to set doc-default-operating-system at install time
 709   tobimensch  Mon, 1 Dec 2014 00:25:07 +0100
 710
 711 - apostrophe (39), circumflex (94), grave (96), tilde (126)
 712   in manuals: \(aq, \(ha, \`, \(ti
 713   Re: [Groff] ASCII Minus Sign in man Pages.
 714   bentley@ 26 Apr 2017 10:02:06 -0600
 715   Do we need to fix existing manuals?
 716   Do we need to fix the definition of the mdoc(7) language?