TODO

   1 ************************************************************************
   2 * Official mandoc TODO.
   3 * $Id: TODO,v 1.208 2015/06/10 22:26:19 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 * crashes
  37 ************************************************************************
  38
  39 - The abort() in bufcat(), html.c, can be triggered via buffmt_includes()
  40   by running -Thtml -Oincludes on a file containing a long .In argument.
  41   Fixing this will probably require reworking the whole bufcat() concept.
  42   loc **  exist *  algo *  size **  imp **
  43
  44 ************************************************************************
  45 * missing features
  46 ************************************************************************
  47
  48 --- missing roff features ----------------------------------------------
  49
  50 - .ad (adjust margins)
  51   .ad l -- adjust left margin only (flush left)
  52   .ad r -- adjust right margin only (flush right)
  53   .ad c -- center text on line
  54   .ad b -- adjust both margins (alias: .ad n)
  55   .na   -- temporarily disable adjustment without changing the mode
  56   .ad   -- re-enable adjustment without changing the mode
  57   Adjustment mode is ignored while in no-fill mode (.nf).
  58   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
  59
  60 - .fc (field control)
  61   found by naddy@ in xloadimage(1)
  62   loc **  exist ***  algo *  size *  imp *
  63
  64 - .nr third argument (auto-increment step size, requires \n+)
  65   found by bentley@ in sbcl(1)  Mon, 9 Dec 2013 18:36:57 -0700
  66   loc *  exist *  algo *  size *  imp **
  67
  68 - .ns (no-space mode) occurs in xine-config(1)
  69   when implementing this, also let .TH set it
  70   reported by brad@  Sat, 15 Jan 2011 15:45:23 -0500
  71   loc ***  exist ***  algo ***  size **  imp *
  72
  73 - .ta (tab settings)
  74   #1 most important issue naddy@ Mon, 16 Feb 2015 20:59:17 +0100
  75   ircbug(1) gnats(1) reported by brad@  Sat, 15 Jan 2011 15:50:51 -0500
  76   also Tcl_NewStringObj(3) via wiz@  Wed, 5 Mar 2014 22:27:43 +0100
  77   also posix2time(3) Carsten Kunze  Mon, 1 Dec 2014 13:03:10 +0100
  78   loc **  exist ***  algo **  size **  imp ***
  79
  80 - .ti (temporary indent)
  81   found by naddy@ in xloadimage(1) [devel/libvstr] vstr(3)
  82   found by bentley@ in nmh(1)  Mon, 23 Apr 2012 13:38:28 -0600
  83   loc **  exist **  algo **  size *  imp ** (parser reorg helps a lot)
  84
  85 - .while and .shift
  86   found by jca@ in ratpoison(1)  Sun, 30 Jun 2013 12:01:09 +0200
  87   loc *  exist **  algo **  size **  imp **
  88
  89 - \h horizontal move
  90   #2 most important issue naddy@  Mon, 16 Feb 2015 20:59:17 +0100
  91   found in cclive(1) nasm(1) bogofilter(1) asciidoc/DocBook output
  92   bentley@ on discuss@  Sat, 21 Sep 2013 22:29:34 -0600
  93   naddy@  Thu, 4 Dec 2014 16:26:41 +0100
  94   loc **  exist **  algo **  size *  imp *** (parser reorg helps a lot)
  95
  96 - \n+ and \n- numerical register increment and decrement
  97   found by bentley@ in sbcl(1)  Mon, 9 Dec 2013 18:36:57 -0700
  98   loc *  exist *  algo *  size *  imp **
  99
 100 - \n(.$ macro argument count number register; ocserv(8) by autogen
 101   found by sthen@  Thu, 19 Feb 2015 22:03:01 +0000
 102   loc *  exist **  algo *  size *  imp **
 103
 104 - \w'' improve width measurements
 105   would not be very useful without an expression parser, see below
 106   needed for Tcl_NewStringObj(3) via wiz@  Wed, 5 Mar 2014 22:27:43 +0100
 107   loc **  exist ***  algo ***  size *  imp ***
 108
 109 - \\ in high-level macro arguments
 110   Currently, \\ is expanded in two situations:
 111   1) macro and string definition (roff.c setstrn())
 112   2) macro argument parsing (mandoc.c mandoc_getarg())
 113   For user defined macros, the second happens in time because of ROFF_REPARSE.
 114   But for standard high-level macros, it only happens after entering the
 115   high level parsers, which is too late because the code doesn't get
 116   back to roff.c roff_res() from that point.  Because this requires
 117   distinguishing requests, user-defined macros and standard macros
 118   on the roff_res() level, it is hard to solve without the parser reorg.
 119   Found by naddy@ in devel/cutils cobfusc(1)  Mon, 16 Feb 2015 19:10:52 +0100
 120   loc ***  exist ***  algo ***  size **  imp *
 121
 122 - using undefined strings or macros defines them to be empty
 123   wl@  Mon, 14 Nov 2011 14:37:01 +0000
 124   loc *  exist *  algo *  size *  imp *
 125
 126 --- missing mdoc features ----------------------------------------------
 127
 128 - .Bl -column .Xo support is missing
 129   ultimate goal:
 130   restore .Xr and .Dv to
 131   lib/libc/compat-43/sigvec.3
 132   lib/libc/gen/signal.3
 133   lib/libc/sys/sigaction.2
 134   loc *  exist ***  algo ***  size *  imp **
 135
 136 - edge case: decide how to deal with blk_full bad nesting, e.g.
 137   .Sh .Nm .Bk .Nm .Ek .Sh found by jmc@ in ssh-keygen(1)
 138   from jmc@  Wed, 14 Jul 2010 18:10:32 +0100
 139   loc *  exist ***  algo ***  size **  imp **
 140
 141 - .Bd -centered implies -filled, not -unfilled, which is not
 142   easy to implement; it requires code similar to .ce, which
 143   we don't have either.
 144   Besides, groff has bug causing text right *before* .Bd -centered
 145   to be centered as well.
 146   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
 147
 148 - .Bd -filled should not be the same as .Bd -ragged, but align both
 149   the left and right margin.  In groff, it is implemented in terms
 150   of .ad b, which we don't have either.  Found in cksum(1).
 151   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
 152
 153 - implement blank `Bl -column', such as
 154   .Bl -column
 155   .It foo Ta bar
 156   .El
 157   loc *  exist ***  algo ***  size *  imp *
 158
 159 - explicitly disallow nested `Bl -column', which would clobber internal
 160   flags defined for struct mdoc_macro
 161   loc *  exist *  algo *  size *  imp **
 162
 163 - In .Bl -column .It, the end of the line probably has to be regarded
 164   as an implicit .Ta, if there could be one, see the following mildly
 165   ugly code from login.conf(5):
 166     .Bl -column minpasswordlen program xetcxmotd
 167     .It path Ta path Ta value of Dv _PATH_DEFPATH
 168     .br
 169     Default search path.
 170   reported by Michal Mazurek <akfaew at jasminek dot net>
 171   via jmc@ Thu, 7 Apr 2011 16:00:53 +0059
 172   loc *  exist ***  algo **  size *  imp **
 173
 174 - inside `.Bl -column' phrases, punctuation is handled like normal
 175   text, e.g. `.Bl -column .It Fl x . Ta ...' should give "-x -."
 176
 177 - inside `.Bl -column' phrases, TERMP_IGNDELIM handling by `Pf'
 178   is not safe, e.g. `.Bl -column .It Pf a b .' gives "ab."
 179   but should give "ab ."
 180
 181 - check whether it is correct that `D1' uses INDENT+1;
 182   does it need its own constant?
 183   loc *  exist **  algo **  size *  imp **
 184
 185 - prohibit `Nm' from having non-text HEAD children
 186   (e.g., NetBSD mDNSShared/dns-sd.1)
 187   (mdoc_html.c and mdoc_term.c `Nm' handlers can be slightly simplified)
 188
 189 - support translated section names
 190   e.g. x11/scrotwm scrotwm_es.1:21:2: error: NAME section must be first
 191   that one uses NOMBRE because it is spanish...
 192   deraadt tends to think that section-dependent macro behaviour
 193   is a bad idea in the first place, so this may be irrelevant
 194   loc **  exist **  algo **  size *  imp **
 195
 196 - When there is free text in the SYNOPSIS and that free text contains
 197   the .Nm macro, groff somehow understands to treat the .Nm as an in-line
 198   macro, while mandoc treats it as a block macro and breaks the line.
 199   No idea how the logic for distinguishing in-line and block instances
 200   should be, needs investigation.
 201   uqs@  Thu, 2 Jun 2011 11:03:51 +0200
 202   uqs@  Thu, 2 Jun 2011 11:33:35 +0200
 203   loc *  exist **  algo ***  size *  imp **
 204
 205 --- missing man features -----------------------------------------------
 206
 207 - -T[x]html doesn't stipulate non-collapsing spaces in literal mode
 208
 209 --- missing tbl features -----------------------------------------------
 210
 211 - support mdoc(7) and man(7) macros inside tbl(7) code;
 212   probably requires the parser reorg and letting tbl(7)
 213   use roff_node such that macro sets can mix;
 214   informed by bapt@ that FreeBSD needs this.
 215   loc ***  exist **  algo ***  size **  imp ***
 216
 217 - look at the POSIX manuals in the books/man-pages-posix port,
 218   they use some unsupported tbl(7) features.
 219   loc *  exist **  algo **  size **  imp ***
 220
 221 - use Unicode U+2500 to U+256C for table borders
 222   in tbl(7) -Tutf-8 output
 223   suggested by bentley@  Tue, 14 Oct 2014 04:10:55 -0600
 224   loc *  exist **  algo *  size *  imp **
 225
 226 - allow standalone `.' to be interpreted as an end-of-layout
 227   delimiter instead of being thrown away as a no-op roff line
 228   reported by Yuri Pankov, Wed 18 May 2011 11:34:59 CEST
 229   loc **  exist **  algo **  size *  imp **
 230
 231 --- missing eqn features -----------------------------------------------
 232
 233 - The "size" keyword is parsed, but ignored by the formatter.
 234   loc *  exist *  algo *  size *  imp *
 235
 236 - The spacing characters `~', `^', and tab are currently ignored,
 237   see User's Guide (Second Edition) page 2 section 4.
 238   loc *  exist *  algo **  size *  imp **
 239
 240 - Mark and lineup are parsed and ignored,
 241   see User's Guide (Second Edition) page 5 section 15.
 242   loc **  exist **  algo **  size **  imp **
 243
 244 --- missing misc features ----------------------------------------------
 245
 246 - italic correction (\/) in PostScript mode
 247   Werner LEMBERG on groff at gnu dot org  Sun, 10 Nov 2013 12:47:46
 248   loc **  exist **  algo *  size *  imp *
 249
 250 - When makewhatis(8) encounters a FATAL parse error,
 251   it silently treats the file as formatted, which makes no sense
 252   at all for paths like man1/foo.1 - and which also contradicts
 253   what the manual says at the end of the description.
 254   The end result will be ENOENT for file names returned
 255   by mansearch() in manpage.file.
 256   loc *  exist *  algo *  size *  imp **
 257
 258 - makewhatis(8) for preformatted pages:
 259   parse the section number from the header line
 260   and compare to the section number from the directory name
 261   loc *  exist *  algo *  size *  imp **
 262
 263 - Does makewhatis(8) detect missing NAME sections, missing names,
 264   and missing descriptions in all the file formats?
 265   loc *  exist *  algo *  size *  imp ***
 266
 267 - clean up escape sequence handling, creating three classes:
 268   (1) fully implemented, or parsed and ignored without loss of content
 269   (2) unimplemented, potentially causing loss of content
 270       or serious mangling of formatting (e.g. \n) -> ERROR
 271       see textproc/mgdiff(1) for nice examples
 272   (3) undefined, just output the character -> perhaps WARNING
 273   loc ***  exist **  algo **  size **  imp *** (parser reorg helps)
 274
 275 - kettenis wants base roff, ms, and me  Fri, 1 Jan 2010 22:13:15 +0100 (CET)
 276   loc **  exist **  algo **  size ***  imp *
 277
 278 - Some FreeBSD people need either a markdown output formatter
 279   for mandoc -mdoc or a markdown to mdoc converter because they
 280   have to maintain manuals needed both in markdown and mdoc format.
 281
 282 --- compatibility checks -----------------------------------------------
 283
 284 - write a configure check for [[:<:]] support and provide some
 285   fallback for whatis(1) when it doesn't work;
 286   Svyatoslav Mishyn  Wed, 17 Dec 2014 11:07:10 +0200
 287
 288 - is .Bk implemented correctly in modern groff?
 289   sobrado@  Tue, 19 Apr 2011 22:12:55 +0200
 290
 291 - compare output to Heirloom roff, Solaris roff, and
 292   http://repo.or.cz/w/neatroff.git  http://litcave.rudi.ir/
 293
 294 - look at AT&T DWB http://www2.research.att.com/sw/download
 295   Carsten Kunze <carsten dot kunze at arcor dot de> has patches
 296   Mon, 4 Aug 2014 17:01:28 +0200
 297
 298 - look at pages generated from reStructeredText, e.g. devel/mercurial hg(1)
 299   These are a weird mixture of man(7) and custom autogenerated low-level
 300   roff stuff.  Figure out to what extent we can cope.
 301   For details, see http://docutils.sourceforge.net/rst.html
 302   noted by stsp@  Sat, 24 Apr 2010 09:17:55 +0200
 303   reminded by nicm@  Mon, 3 May 2010 09:52:41 +0100
 304
 305 - look at pages generated from ronn(1) github.com/rtomayko/ronn
 306   (based on markdown)
 307
 308 - look at pages generated from Texinfo source by yat2m, e.g. security/gnupg
 309   First impression is not that bad.
 310
 311 - look at pages generated by pandoc; see
 312   https://github.com/jgm/pandoc/blob/master/src/Text/Pandoc/Writers/Man.hs
 313   porting planned by kili@  Thu, 19 Jun 2014 19:46:28 +0200
 314
 315 - check compatibility with Plan9:
 316   http://swtch.com/usr/local/plan9/tmac/tmac.an
 317   http://swtch.com/plan9port/man/man7/man.html
 318   "Anthony J. Bentley" <anthonyjbentley@gmail.com> 28 Dec 2010 21:58:40 -0700
 319
 320 - check compatibility with COHERENT troff:
 321   http://www.nesssoftware.com/home/mwc/source.php
 322
 323 - check compatibility with the man(7) formatter
 324   https://raw.githubusercontent.com/rofl0r/hardcore-utils/master/man.c
 325
 326 - check compatibility with
 327   http://ikiwiki.info/plugins/contrib/mandoc/
 328   https://github.com/schmonz/ikiwiki/compare/mandoc
 329   Amitai Schlair  Mon, 19 May 2014 14:05:53 -0400
 330
 331 ************************************************************************
 332 * formatting issues: ugly output
 333 ************************************************************************
 334
 335 - revisit empty in-line macros
 336   look at the difference between "Em x Em ." and "Sq x Em ."
 337   Carsten Kunze  Fri, 12 Dec 2014 00:15:41 +0100
 338   loc *** exist *** algo *** size * imp **
 339
 340 - a column list with blank `Ta' cells triggers a spurious
 341   start-with-whitespace printing of a newline
 342
 343 - In .Bl -column, .It a<tab>"b<tab>c"
 344   shows the quotes in groff, but not in mandoc
 345   loc * exist *** algo ** size * imp **
 346
 347 - In .Bl -column,
 348   .It Em Authentication<tab>Key Length
 349   ought to render "Key Length" with emphasis, too,
 350   see OpenBSD iked.conf(5).
 351   reported again Nicolas Joly via wiz@ Wed, 12 Oct 2011 00:20:00 +0200
 352   loc *  exist ***  algo ***  size **  imp ***
 353
 354 - empty phrases in .Bl column produce too few blanks
 355   try e.g. .Bl -column It Ta Ta
 356   reported by millert Fri, 02 Apr 2010 16:13:46 -0400
 357   loc *  exist ***  algo ***  size *  imp **
 358
 359 - .%T can have trailing punctuation.  Currently, it puts the trailing
 360   punctuation into a trailing MDOC_TEXT element inside its own scope.
 361   That element should rather be outside its scope, such that the
 362   punctuation does not get underlines.  This is not trivial to
 363   implement because .%T then needs some features of in_line_eoln() -
 364   slurp all arguments into one single text element - and one feature
 365   of in_line() - put trailing punctuation out of scope.
 366   Found in mount_nfs(8) and exports(5), search for "Appendix".
 367   loc **  exist **  algo ***  size *  imp **
 368
 369 - Trailing punctuation after .%T triggers EOS spacing, at least
 370   outside .Rs (eek!).  Simply setting ARGSFL_DELIM for .%T is not
 371   the right solution, it sends mandoc into an endless loop.
 372   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 373   loc *  exist **  algo **  size *  imp **
 374
 375 - global variables in the SYNOPSIS of section 3 pages
 376   .Vt vs .Vt/.Va vs .Ft/.Va vs .Ft/.Fa ...
 377   from kristaps@  Tue, 08 Jun 2010 11:13:32 +0200
 378
 379 - in enclosures, mandoc sometimes fancies a bogus end of sentence
 380   reminded by jmc@  Thu, 23 Sep 2010 18:13:39 +0059
 381   loc *  exist **  algo ***  size *  imp ***
 382
 383 - a line starting with "\fB something" counts as starting with whitespace
 384   and triggers a line break; found in audio/normalize-mp3(1)
 385   loc **  exist *  algo **  size *  imp **
 386
 387 - formatting /usr/local/man/man1/latex2man.1 with groff and mandoc
 388   reveals lots of bugs both in groff and mandoc...
 389   reported by bentley@  Wed, 22 May 2013 23:49:30 -0600
 390
 391 --- PDF issues ---------------------------------------------------------
 392
 393 - PDF output doesn't use a monospaced font for .Bd -literal
 394   Example: "mandoc -Tpdf afterboot.8 > output.pdf && pdfviewer output.pdf".
 395   Search the text "Routing tables".
 396   Also check what PostScript mode does when fixing this.
 397   reported by juanfra@ Wed, 04 Jun 2014 21:44:58 +0200
 398   instructions from juanfra@  Wed, 11 Jun 2014 02:21:01 +0200
 399     add a new <</Type /Font>> block to the PDF files with /BaseFont /Courier
 400     and change the /Name from /F0 to the new font (/F5 (?)).
 401   loc *  exist **  algo **  size *  imp **
 402
 403 --- HTML issues --------------------------------------------------------
 404
 405 - <dl><dt><dd> formatting is ugly
 406   hints are easy to find on the web, e.g.
 407   http://stackoverflow.com/questions/1713048/
 408   see also matthew@  Fri, 18 Jul 2014 19:25:12 -0700
 409   loc *  exist *  algo **  size *  imp ***
 410
 411 - jsg on icb, Nov 3, 2014:
 412   try to guess Xr in man(7) for hyperlinking
 413
 414 - The tables used to render the three-part page headers actually force
 415   the width of the <body> to the max-width given for <html>.
 416   Not yet sure how to fix that...
 417   Observed by an Anonymous Coward on undeadly.org:
 418   http://undeadly.org/cgi?action=article&sid=20140925064244&pid=1
 419   loc *  exist *  algo **  size *  imp ***
 420
 421 - consider whether <var> can be used for Ar Dv Er Ev Fa Va.
 422   from bentley@  Wed, 13 Aug 2014 09:17:55 -0600
 423
 424 - generate <img> tags in HTML
 425   idea from florian@  Tue, 7 Apr 2015 00:26:28 +0000
 426   may be possible to implement with .Lk img://something.png alt_text
 427
 428 - check https://github.com/trentm/mdocml
 429
 430 ************************************************************************
 431 * formatting issues: gratuitous differences
 432 ************************************************************************
 433
 434 - .Fn reopens a new scope after punctuation in mandoc,
 435   but closes its scope for good in groff.
 436   Do we want to change mandoc or groff?
 437   Steffen Nurpmeso  Sat, 08 Nov 2014 13:34:59 +0100
 438   loc *  exist **  algo **  size *  imp **
 439
 440 - In .Bl -enum -width 0n, groff continues one the same line after
 441   the number, mandoc breaks the line.
 442   mail to kristaps@  Mon, 20 Jul 2009 02:21:39 +0200
 443   loc *  exist **  algo **  size *  imp **
 444
 445 - .Pp between two .It in .Bl -column should produce one,
 446   not two blank lines, see e.g. login.conf(5).
 447   reported by jmc@  Sun, 17 Apr 2011 14:04:58 +0059
 448   reported again by sthen@  Wed, 18 Jan 2012 02:09:39 +0000 (UTC)
 449   loc *  exist ***  algo **  size *  imp **
 450
 451 - If the *first* line after .It is .Pp, break the line right after
 452   the tag, do not pad with space characters before breaking.
 453   See the description of the a, c, and i commands in sed(1).
 454   loc *  exist **  algo **  size *  imp **
 455
 456 - If the first line after .It is .D1, do not assert a blank line
 457   in between, see for example tmux(1).
 458   reported by nicm@  13 Jan 2011 00:18:57 +0000
 459   loc *  exist **  algo **  size *  imp **
 460
 461 - Trailing punctuation after .It should trigger EOS spacing.
 462   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 463   Probably, this should be fixed somewhere in termp_it_pre(), not sure.
 464   loc *  exist **  algo **  size *  imp **
 465
 466 - .Nx 1.0a
 467   should be "NetBSD 1.0A", not "NetBSD 1.0a",
 468   see OpenBSD ccdconfig(8).
 469   loc *  exist *  algo *  size *  imp **
 470
 471 - In .Bl -tag, if a tag exceeds the right margin and must be continued
 472   on the next line, it must be indented by -width, not width+1;
 473   see "rule block|pass" in OpenBSD ifconfig(8).
 474   loc *  exist ***  algo **  size *  imp **
 475
 476 - When the -width string contains macros, the macros must be rendered
 477   before measuring the width, for example
 478     .Bl -tag -width ".Dv message"
 479   in magic(5), located in src/usr.bin/file, is the same
 480   as -width 7n, not -width 11n.
 481   The same applies to .Bl -column column widths;
 482   reported again by Nicolas Joly Thu, 1 Mar 2012 13:41:26 +0100 via wiz@ 5 Mar
 483   reported again by Franco Fichtner Fri, 27 Sep 2013 21:02:28 +0200
 484   loc ***  exist ***  algo ***  size **  imp ***
 485   An easy partial fix would be to just skip the first word if it starts
 486   with a dot, including any following white space, when measuring.
 487   loc *  exist *  algo *  size *  imp ***
 488
 489 - The \& zero-width character counts as output.
 490   That is, when it is alone on a line between two .Pp,
 491   we want three blank lines, not two as in mandoc.
 492   loc **  exist **  algo **  size *  imp **
 493
 494 - Header lines of excessive length:
 495   Port OpenBSD man_term.c rev. 1.25 to mdoc_term.c
 496   and document it in mdoc(7) and man(7) COMPATIBILITY
 497   found while talking to Chris Bennett
 498   loc *  exist *  algo *  size *  imp *
 499
 500 - Sequences of multiple man(7) paragraphs (.PP, .IP) interspersed
 501   with .ps and .nf/.fi produce execessive blank lines, see libJudy
 502   and graphics/dcmtk.  The parser reorg may help with this.
 503
 504 - trailing whitespace must be ignored even when followed by a font escape,
 505   see for example
 506     makes
 507     \fBdig \fR
 508     operate in batch mode
 509   in dig(1).
 510   loc **  exist **  algo **  size *  imp **
 511
 512 ************************************************************************
 513 * portability
 514 ************************************************************************
 515
 516 - word boundaries in regular expressions for whatis(1)
 517   set up config tests to use [[:<:]], \<, or nothing
 518   reminded by Peter Bray Fri, 03 Apr 2015 23:02:16 +1100
 519
 520 ************************************************************************
 521 * warning issues
 522 ************************************************************************
 523
 524 - check that MANDOCERR_BADTAB is thrown in the right cases,
 525   i.e. when finding a literal tab character in fill mode,
 526   and possibly change the wording of the warning message
 527   to refer to fill mode, not literal mode
 528   See the mail from Werner LEMBERG on the groff list,
 529   Fri, 14 Feb 2014 18:54:42 +0100 (CET)
 530   loc *  exist **  algo **  size *  imp **
 531
 532 - warn about attempts to call non-callable macros
 533   Steffen Nurpmeso  Tue, 11 Nov 2014 22:55:16 +0100
 534   Note that formatting is inconsistent in groff.
 535   .Fn Po prints "Po()", .Ar Sh prints "file ..." and no "Sh".
 536   Relatively hard because the relevant code is scattered
 537   all over mdoc_macro.c and all subtly different.
 538   loc **  exist **  algo **  size **  imp **
 539
 540 - warn about "new sentence, new line"
 541   loc **  exist **  algo ***  size *  imp **
 542
 543 - mandoc_special does not really check the escape sequence,
 544   but just the overall format
 545   loc **  exist **  algo ***  size **  imp **
 546
 547 - integrate mdoclint into mandoc ("end-of-line whitespace" thread)
 548   from jmc@  Mon, 13 Jul 2009 17:12:09 +0100
 549   from kristaps@  Mon, 13 Jul 2009 18:34:53 +0200
 550   from jmc@  Mon, 13 Jul 2009 17:45:37 +0059
 551   from kristaps@  Mon, 13 Jul 2009 19:02:03 +0200
 552   (mostly done, check what remains)
 553
 554 - -Tlint parser errors and warnings to stdout
 555   to tech@mdocml, naddy@  Wed, 28 Sep 2011 11:21:46 +0200
 556   wait!  kristaps@  Sun, 02 Oct 2011 17:12:52 +0200
 557
 558 - for system errors, use errno/strerror/warn/err
 559
 560 ************************************************************************
 561 * documentation issues
 562 ************************************************************************
 563
 564 - mention hyphenation rules:
 565   breaking at letter-letter in text mode (not macro args)
 566   proper hyphenation is unimplemented
 567
 568 - talk about spacing around delimiters
 569   to jmc@, kristaps@  Sat, 23 Apr 2011 17:41:27 +0200
 570
 571 - mark macros as: page structure domain, manual domain, general text domain
 572   is this useful?
 573
 574 - mention /usr/share/misc/mdoc.template in mdoc(7)?
 575
 576 - Is all the content from http://www.std.com/obi/BSD/doc/usd/28.tbl/tbl
 577   covered in tbl(7)?
 578
 579 ************************************************************************
 580 * performance issues
 581 ************************************************************************
 582
 583 - Why are we using MAP_SHARED, not MAP_PRIVATE for mmap(2)?
 584   How does SQLITE_CONFIG_PAGECACHE actually work?  Document it!
 585   from kristaps@  Sat, 09 Aug 2014 13:51:36 +0200
 586
 587 Several areas can be cleaned up to make mandoc even faster.  These are
 588
 589 - improve hashing mechanism for macros (quite important: performance)
 590
 591 - improve hashing mechanism for characters (not as important)
 592
 593 - the PDF file is HUGE: this can be reduced by using relative offsets
 594
 595 - instead of re-initialising the roff predefined-strings set before each
 596   parse, create a read-only version the first time and copy it
 597   loc *  exist **  algo **  size *  imp **
 598
 599 ************************************************************************
 600 * structural issues
 601 ************************************************************************
 602
 603 - Improve -O suboption parsing.  Do it in the main program such that
 604   errors can be reported.  Pay attention to distinguishing the
 605   mandoc(1) and apropos(1) styles of both options.
 606   loc **  exist *  algo **  size **  imp ***
 607
 608 - Use libz directly instead of forking gunzip(1).
 609   Suggested by bapt at FreeBSD among others.
 610
 611 - We use the input line number at several places to distinguish
 612   same-line from different-line input.  That plainly doesn't work
 613   with user-defined macros, leading to random breakage.
 614
 615 - Find better ways to prevent endless loops
 616   in roff(7) macro and string expansion.
 617
 618 - Finish cleanup of date handling.
 619   Decide which formats should be recognized where.
 620   Update both mdoc(7) and man(7) documentation.
 621   Triggered by  Tim van der Molen  Tue, 22 Feb 2011 20:30:45 +0100
 622
 623 - struct mparse refactoring
 624   Steffen Nurpmeso  Thu, 04 Sep 2014 12:50:00 +0200
 625
 626 - Consider creating some views that will make the database more
 627   readable from the sqlite3 shell.  Consider using them to
 628   abstract from the database structure, too.
 629   suggested by espie@  Sat, 19 Apr 2014 14:52:57 +0200
 630
 631 ************************************************************************
 632 * CGI issues
 633 ************************************************************************
 634
 635  - Enable HTTP compression by detecting gzip encoding and filtering
 636    output through libz.
 637  - Sandbox (see OpenSSH).
 638  - Enable caching support via HTTP 304 and If-Modified-Since.
 639  - Allow for cgi.h to be overridden by CGI environment variables.
 640    Otherwise, binary distributions will inherit the compile-time
 641    behaviour, which is not optimal.
 642  - Have Mac OSX systems automatically disable -static compilation of the
 643    CGI: -static isn't supported.
 644
 645 ************************************************************************
 646 * to improve in the groff_mdoc(7) macros
 647 ************************************************************************
 648
 649 - use uname(1) to set doc-default-operating-system at install time
 650   tobimensch  Mon, 1 Dec 2014 00:25:07 +0100