TODO

   1 ************************************************************************
   2 * Official mandoc TODO.
   3 * $Id: TODO,v 1.283 2019/01/17 08:14:38 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 * missing features
  37 ************************************************************************
  38
  39 --- missing roff features ----------------------------------------------
  40
  41 - .ad (adjust margins)
  42   .ad l -- adjust left margin only (flush left)
  43   .ad r -- adjust right margin only (flush right)
  44   .ad c -- center text on line
  45   .ad b -- adjust both margins (alias: .ad n)
  46   .na   -- temporarily disable adjustment without changing the mode
  47   .ad   -- re-enable adjustment without changing the mode
  48   Adjustment mode is ignored while in no-fill mode (.nf).
  49   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
  50
  51 - .fc (field control)
  52   found by naddy@ in xloadimage(1)
  53   loc **  exist ***  algo *  size *  imp *
  54
  55 - .ns (no-space mode) occurs in xine-config(1)
  56   when implementing this, also let .TH set it
  57   reported by brad@  Sat, 15 Jan 2011 15:45:23 -0500
  58   loc ***  exist ***  algo ***  size **  imp *
  59
  60 - \w'' improve width measurements
  61   would not be very useful without an expression parser, see below
  62   needed for Tcl_NewStringObj(3) via wiz@  Wed, 5 Mar 2014 22:27:43 +0100
  63   loc **  exist ***  algo ***  size *  imp ***
  64
  65 --- missing mdoc features ----------------------------------------------
  66
  67 - .Bl -column .Xo support is missing
  68   ultimate goal:
  69   restore .Xr and .Dv to
  70   lib/libc/compat-43/sigvec.3
  71   lib/libc/gen/signal.3
  72   lib/libc/sys/sigaction.2
  73   loc *  exist ***  algo ***  size *  imp **
  74
  75 - edge case: decide how to deal with blk_full bad nesting, e.g.
  76   .Sh .Nm .Bk .Nm .Ek .Sh found by jmc@ in ssh-keygen(1)
  77   from jmc@  Wed, 14 Jul 2010 18:10:32 +0100
  78   loc *  exist ***  algo ***  size **  imp **
  79
  80 - .Bd -filled should not be the same as .Bd -ragged, but align both
  81   the left and right margin.  In groff, it is implemented in terms
  82   of .ad b, which we don't have either.  Found in cksum(1).
  83   loc ***  exist ***  algo **  size **  imp **  (parser reorg would help)
  84
  85 - implement blank `Bl -column', such as
  86   .Bl -column
  87   .It foo Ta bar
  88   .El
  89   loc *  exist ***  algo ***  size *  imp *
  90
  91 - explicitly disallow nested `Bl -column', which would clobber internal
  92   flags defined for struct mdoc_macro
  93   loc *  exist *  algo *  size *  imp **
  94
  95 - In .Bl -column .It, the end of the line probably has to be regarded
  96   as an implicit .Ta, if there could be one, see the following mildly
  97   ugly code from login.conf(5):
  98     .Bl -column minpasswordlen program xetcxmotd
  99     .It path Ta path Ta value of Dv _PATH_DEFPATH
 100     .br
 101     Default search path.
 102   reported by Michal Mazurek <akfaew at jasminek dot net>
 103   via jmc@ Thu, 7 Apr 2011 16:00:53 +0059
 104   loc *  exist ***  algo **  size *  imp **
 105
 106 - inside `.Bl -column' phrases, punctuation is handled like normal
 107   text, e.g. `.Bl -column .It Fl x . Ta ...' should give "-x -."
 108
 109 - inside `.Bl -column' phrases, TERMP_IGNDELIM handling by `Pf'
 110   is not safe, e.g. `.Bl -column .It Pf a b .' gives "ab."
 111   but should give "ab ."
 112
 113 - prohibit `Nm' from having non-text HEAD children
 114   (e.g., NetBSD mDNSShared/dns-sd.1)
 115   (mdoc_html.c and mdoc_term.c `Nm' handlers can be slightly simplified)
 116
 117 - support translated section names
 118   e.g. x11/scrotwm scrotwm_es.1:21:2: error: NAME section must be first
 119   that one uses NOMBRE because it is spanish...
 120   deraadt tends to think that section-dependent macro behaviour
 121   is a bad idea in the first place, so this may be irrelevant
 122   loc **  exist **  algo **  size *  imp **
 123
 124 - When there is free text in the SYNOPSIS and that free text contains
 125   the .Nm macro, groff somehow understands to treat the .Nm as an in-line
 126   macro, while mandoc treats it as a block macro and breaks the line.
 127   No idea how the logic for distinguishing in-line and block instances
 128   should be, needs investigation.
 129   uqs@  Thu, 2 Jun 2011 11:03:51 +0200
 130   uqs@  Thu, 2 Jun 2011 11:33:35 +0200
 131   loc *  exist **  algo ***  size *  imp **
 132
 133 --- missing man features -----------------------------------------------
 134
 135 - groff_www(7) .MTO and .URL
 136   These macros were used by the GNU grep(1) man page.
 137   The groff_www(7) manual page itself uses them, too.
 138   We should probably *not* add them to mandoc.
 139   Just mentioning this here to keep track of the abuse.
 140   Laura Morales <lauretas at mail dot com> 20 Apr 2018 07:33:02 +0200
 141   loc **  exist *  algo *  size **  imp *
 142
 143 --- missing tbl features -----------------------------------------------
 144
 145 - vertical centering in cells vertically spanned with ^
 146   pali dot rohar at gmail dot com 16 Jul 2018 13:03:35 +0200
 147   loc *  exist ***  algo ***  size **  imp *
 148
 149 - support mdoc(7) and man(7) macros inside tbl(7) code;
 150   probably requires the parser reorg and letting tbl(7)
 151   use roff_node such that macro sets can mix;
 152   informed by bapt@ that FreeBSD needs this: 3 Jan 2015 23:32:23 +0100
 153   loc ***  exist **  algo ***  size **  imp ***
 154
 155 - look at the POSIX manuals in the books/man-pages-posix port,
 156   they use some unsupported tbl(7) features, mostly macros in tbl(7).
 157   loc *  exist **  algo **  size **  imp ***
 158
 159 - look what Joerg Schilling manual pages use
 160   Thu, 19 Mar 2015 18:31:48 +0100
 161
 162 --- missing eqn features -----------------------------------------------
 163
 164 - In a matrix, break the output line after each matrix line.
 165   Found in the discussion at CDBUG 2015.
 166   Suggested by Avi Weinstock.
 167   loc *  exist *  algo *  size *  imp **
 168
 169 - The "size" keyword is parsed, but ignored by the formatter.
 170   loc *  exist *  algo *  size *  imp *
 171
 172 - The spacing characters `~', `^', and tab are currently ignored,
 173   see User's Guide (Second Edition) page 2 section 4.
 174   loc *  exist *  algo **  size *  imp **
 175
 176 - Mark and lineup are parsed and ignored,
 177   see User's Guide (Second Edition) page 5 section 15.
 178   loc **  exist **  algo **  size **  imp **
 179
 180 - GNU eqn converts some operators to special characters, for example,
 181   input HYPHEN-MINUS becomes output \(mi, unless it is part of a
 182   quoted word.  mandoc(1) only does this when the operator is
 183   surrounded by blanks, not when it is part of an unquoted word.
 184   Also, check whether there are more such cases (e.g., +?).
 185   reported by bentley@  20 Jun 2017 02:04:29 -0600
 186   loc *  exist **  algo **  size *  imp *
 187
 188 - Primes, opprime, and '
 189   bentley@  Thu, 13 Jul 2017 23:14:20 -0600
 190
 191 --- missing misc features ----------------------------------------------
 192
 193 - man -ks 1,8 route; kn@ Jul 13, 2018 orally
 194
 195 - italic correction (\/) in PostScript mode
 196   Werner LEMBERG on groff at gnu dot org  Sun, 10 Nov 2013 12:47:46
 197   loc **  exist **  algo *  size *  imp *
 198
 199 - change the default PAGER to more -Es and use the pager
 200   even for apropos title line output; req by bapt@
 201   loc *  exist *  algo *  size *  imp ***
 202
 203 - clean up escape sequence handling, creating three classes:
 204   (1) fully implemented, or parsed and ignored without loss of content
 205   (2) unimplemented, potentially causing loss of content
 206       or serious mangling of formatting (e.g. \n) -> ERROR
 207       see textproc/mgdiff(1) for nice examples
 208   (3) undefined, just output the character -> perhaps WARNING
 209   loc ***  exist **  algo **  size **  imp *** (parser reorg helps)
 210
 211 - kettenis wants base roff, ms, and me  Fri, 1 Jan 2010 22:13:15 +0100 (CET)
 212   loc **  exist **  algo **  size ***  imp *
 213
 214 --- compatibility checks -----------------------------------------------
 215
 216 - is .Bk implemented correctly in modern groff?
 217   sobrado@  Tue, 19 Apr 2011 22:12:55 +0200
 218
 219 - compare output to Heirloom roff, Solaris roff, and
 220   http://repo.or.cz/w/neatroff.git  http://litcave.rudi.ir/
 221
 222 - look at AT&T DWB http://www2.research.att.com/sw/download
 223   Carsten Kunze <carsten dot kunze at arcor dot de> has patches
 224   Mon, 4 Aug 2014 17:01:28 +0200
 225   ported version: https://github.com/n-t-roff/DWB3.3
 226   Carsten Kunze  Wed, 22 Apr 2015 11:21:43 +0200
 227
 228 - look at pages generated from reStructeredText, e.g. devel/mercurial hg(1)
 229   These are a weird mixture of man(7) and custom autogenerated low-level
 230   roff stuff.  Figure out to what extent we can cope.
 231   For details, see http://docutils.sourceforge.net/rst.html
 232   noted by stsp@  Sat, 24 Apr 2010 09:17:55 +0200
 233   reminded by nicm@  Mon, 3 May 2010 09:52:41 +0100
 234
 235 - look at pages generated from ronn(1) github.com/rtomayko/ronn
 236   (based on markdown)
 237
 238 - look at pages generated from Texinfo source by yat2m, e.g. security/gnupg
 239   First impression is not that bad.
 240
 241 - look at pages generated by pandoc; see
 242   https://github.com/jgm/pandoc/blob/master/src/Text/Pandoc/Writers/Man.hs
 243   porting planned by kili@  Thu, 19 Jun 2014 19:46:28 +0200
 244
 245 - check compatibility with Plan9:
 246   http://swtch.com/usr/local/plan9/tmac/tmac.an
 247   http://swtch.com/plan9port/man/man7/man.html
 248   "Anthony J. Bentley" <anthonyjbentley@gmail.com> 28 Dec 2010 21:58:40 -0700
 249
 250 - check compatibility with COHERENT troff:
 251   http://www.nesssoftware.com/home/mwc/source.php
 252
 253 - check compatibility with the man(7) formatter
 254   https://raw.githubusercontent.com/rofl0r/hardcore-utils/master/man.c
 255
 256 - check compatibility with
 257   http://ikiwiki.info/plugins/contrib/mandoc/
 258   https://github.com/schmonz/ikiwiki/compare/mandoc
 259   Amitai Schlair  Mon, 19 May 2014 14:05:53 -0400
 260
 261 - check features of the Slackware man.conf(5) format
 262   Carsten Kunze  Wed, 11 Mar 2015 17:57:24 +0100
 263
 264 ************************************************************************
 265 * formatting issues: ugly output
 266 ************************************************************************
 267
 268 - revisit empty in-line macros
 269   look at the difference between "Em x Em ." and "Sq x Em ."
 270   Carsten Kunze  Fri, 12 Dec 2014 00:15:41 +0100
 271   loc *** exist *** algo *** size * imp **
 272
 273 - a column list with blank `Ta' cells triggers a spurious
 274   start-with-whitespace printing of a newline
 275
 276 - In .Bl -column, .It a<tab>"b<tab>c"
 277   shows the quotes in groff, but not in mandoc
 278   loc * exist *** algo ** size * imp **
 279
 280 - In .Bl -column,
 281   .It Em Authentication<tab>Key Length
 282   ought to render "Key Length" with emphasis, too,
 283   see OpenBSD iked.conf(5).
 284   reported again Nicolas Joly via wiz@ Wed, 12 Oct 2011 00:20:00 +0200
 285   loc *  exist ***  algo ***  size **  imp ***
 286
 287 - empty phrases in .Bl column produce too few blanks
 288   try e.g. .Bl -column It Ta Ta
 289   reported by millert Fri, 02 Apr 2010 16:13:46 -0400
 290   loc *  exist ***  algo ***  size *  imp **
 291
 292 - .%T can have trailing punctuation.  Currently, it puts the trailing
 293   punctuation into a trailing MDOC_TEXT element inside its own scope.
 294   That element should rather be outside its scope, such that the
 295   punctuation does not get underlines.  This is not trivial to
 296   implement because .%T then needs some features of in_line_eoln() -
 297   slurp all arguments into one single text element - and one feature
 298   of in_line() - put trailing punctuation out of scope.
 299   Found in mount_nfs(8) and exports(5), search for "Appendix".
 300   loc **  exist **  algo ***  size *  imp **
 301
 302 - Trailing punctuation after .%T triggers EOS spacing, at least
 303   outside .Rs (eek!).  Simply setting ARGSFL_DELIM for .%T is not
 304   the right solution, it sends mandoc into an endless loop.
 305   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 306   loc *  exist **  algo **  size *  imp **
 307
 308 - global variables in the SYNOPSIS of section 3 pages
 309   .Vt vs .Vt/.Va vs .Ft/.Va vs .Ft/.Fa ...
 310   from kristaps@  Tue, 08 Jun 2010 11:13:32 +0200
 311
 312 - implicit whitespace around inline equations
 313   example code:  where '$times$' denotes matrix multiplication
 314   must not have an HTML line break, nor a blank, before <math>
 315   partial solution: html.c {"math", HTML_NLINSIDE | HTML_INDENT},
 316   bentley@  Thu, 13 Jul 2017 19:00:59 -0600
 317
 318 - in enclosures, mandoc sometimes fancies a bogus end of sentence
 319   reminded by jmc@  Thu, 23 Sep 2010 18:13:39 +0059
 320   loc *  exist **  algo ***  size *  imp ***
 321
 322 - a line starting with "\fB something" counts as starting with whitespace
 323   and triggers a line break; found in audio/normalize-mp3(1)
 324   loc **  exist *  algo **  size *  imp **
 325
 326 - formatting /usr/local/man/man1/latex2man.1 with groff and mandoc
 327   reveals lots of bugs both in groff and mandoc...
 328   reported by bentley@  Wed, 22 May 2013 23:49:30 -0600
 329
 330 --- PostScript and PDF issues ------------------------------------------
 331
 332 - PDF output doesn't use a monospaced font for .Bd -literal
 333   Example: "mandoc -Tpdf afterboot.8 > output.pdf && pdfviewer output.pdf".
 334   Search the text "Routing tables".
 335   Also check what PostScript mode does when fixing this.
 336   reported by juanfra@ Wed, 04 Jun 2014 21:44:58 +0200
 337   instructions from juanfra@  Wed, 11 Jun 2014 02:21:01 +0200
 338     add a new <</Type /Font>> block to the PDF files with /BaseFont /Courier
 339     and change the /Name from /F0 to the new font (/F5 (?)).
 340   re-reported by tb@ Mon, 16 Mar 2015 16:47:21 +0100
 341   loc *  exist **  algo **  size *  imp **
 342
 343 --- HTML issues --------------------------------------------------------
 344
 345 - wrap Sh and Ss content into <div>
 346   Laura Morales <lauretas at mail dot com> 21 Apr 2018 18:10:48 +0200
 347   (Evaluate whether this is really useful and has no adverse
 348    side effects before implementing; if it is possible,
 349    it does seem cleaner.)
 350   loc **  exist **  algo *  size *  imp ***
 351
 352 - format multiple subsequent .IP as a single list
 353   rather than opening a new list for each item
 354   Pali Rohar 25 Nov 2018 14:34:26 +0100
 355   loc *  exist **  algo *  size *  imp ***
 356
 357 - format ".IP *" etc. as <ul> rather than <dl>
 358   https://github.com/Debian/debiman/issues/67
 359   reminded by Pali Rohar 25 Nov 2018 14:34:26 +0100
 360   loc ** exist ** algo ** size * imp ***
 361
 362 - .Bf at the beginning of a paragraph inserts a bogus 1ex horizontal
 363   space, see for example random(3).  Introduced in
 364   http://mdocml.bsd.lv/cgi-bin/cvsweb/mdoc_html.c.diff?r1=1.91&r2=1.92
 365   reported by deraadt@ Mon, 28 Sep 2015 20:14:13 -0600 (MDT)
 366   loc **  exist **  algo **  size *  imp *
 367
 368 - jsg on icb, Nov 3, 2014:
 369   try to guess Xr in man(7) for hyperlinking
 370   and render them with <a class="Xr" href=...>
 371   https://github.com/Debian/debiman/issues/15
 372   loc *  exist *  algo **  size **  imp **
 373
 374 - The tables used to render the three-part page headers actually force
 375   the width of the <body> to the max-width given for <html>.
 376   Not yet sure how to fix that...
 377   Observed by an Anonymous Coward on undeadly.org:
 378   http://undeadly.org/cgi?action=article&sid=20140925064244&pid=1
 379   loc *  exist *  algo **  size *  imp ***
 380
 381 - generate <img> tags in HTML
 382   idea from florian@  Tue, 7 Apr 2015 00:26:28 +0000
 383   may be possible to implement with .Lk img://something.png alt_text
 384
 385 - check https://github.com/trentm/mdocml
 386
 387 ************************************************************************
 388 * formatting issues: gratuitous differences
 389 ************************************************************************
 390
 391 - .Fn reopens a new scope after punctuation in mandoc,
 392   but closes its scope for good in groff.
 393   Do we want to change mandoc or groff?
 394   Steffen Nurpmeso  Sat, 08 Nov 2014 13:34:59 +0100
 395   loc *  exist **  algo **  size *  imp **
 396
 397 - In .Bl -enum -width 0n, groff continues one the same line after
 398   the number, mandoc breaks the line.
 399   mail to kristaps@  Mon, 20 Jul 2009 02:21:39 +0200
 400   loc *  exist **  algo **  size *  imp **
 401
 402 - .Pp between two .It in .Bl -column should produce one,
 403   not two blank lines, see e.g. login.conf(5).
 404   reported by jmc@  Sun, 17 Apr 2011 14:04:58 +0059
 405   reported again by sthen@  Wed, 18 Jan 2012 02:09:39 +0000 (UTC)
 406   loc *  exist ***  algo **  size *  imp **
 407
 408 - If the *first* line after .It is .Pp, break the line right after
 409   the tag, do not pad with space characters before breaking.
 410   See the description of the a, c, and i commands in sed(1).
 411   loc *  exist **  algo **  size *  imp **
 412
 413 - If the first line after .It is .D1, do not assert a blank line
 414   in between, see for example tmux(1).
 415   reported by nicm@  13 Jan 2011 00:18:57 +0000
 416   loc *  exist **  algo **  size *  imp **
 417
 418 - Trailing punctuation after .It should trigger EOS spacing.
 419   reported by Nicolas Joly  Sat, 17 Nov 2012 11:49:54 +0100
 420   Probably, this should be fixed somewhere in termp_it_pre(), not sure.
 421   loc *  exist **  algo **  size *  imp **
 422
 423 - When the -width string contains macros, the macros must be rendered
 424   before measuring the width, for example
 425     .Bl -tag -width ".Dv message"
 426   in magic(5), located in src/usr.bin/file, is the same
 427   as -width 7n, not -width 11n.
 428   The same applies to .Bl -column column widths;
 429   reported again by Nicolas Joly Thu, 1 Mar 2012 13:41:26 +0100 via wiz@ 5 Mar
 430   reported again by Franco Fichtner Fri, 27 Sep 2013 21:02:28 +0200
 431   reported again by Bruce Evans Fri, 17 Feb 2017 21:22:44 +0100 via bapt@
 432   loc ***  exist ***  algo ***  size **  imp ***
 433   An easy partial fix would be to just skip the first word if it starts
 434   with a dot, including any following white space, when measuring.
 435   loc *  exist *  algo *  size *  imp ***
 436
 437 - The \& zero-width character counts as output.
 438   That is, when it is alone on a line between two .Pp,
 439   we want three blank lines, not two as in mandoc.
 440   loc **  exist **  algo **  size *  imp **
 441
 442 - Sequences of multiple man(7) paragraphs (.PP, .IP) interspersed
 443   with .ps and .nf/.fi produce execessive blank lines, see libJudy
 444   and graphics/dcmtk.  The parser reorg may help with this.
 445
 446 - trailing whitespace must be ignored even when followed by a font escape,
 447   see for example
 448     makes
 449     \fBdig \fR
 450     operate in batch mode
 451   in dig(1).
 452   loc **  exist **  algo **  size *  imp **
 453
 454 ************************************************************************
 455 * warning issues
 456 ************************************************************************
 457
 458 - When a man(1) command returns no result and there was an -S
 459   argument, check the -S argument against the list of valid
 460   architectures and say "Unknown architecture AAA" rather than
 461   "No entry for NNN in the manual" if there is no match.
 462   Requires moving the lists of valid architectures out of
 463   mdoc_validate.c such that they can be used by main.c.
 464   Discussed with jmc@ 10 Aug 2018 19:20:12 +0100.
 465   loc **  exist *  algo *  size *  imp **
 466
 467 - warn about duplicate .Sh/.Ss heads
 468   gre(4): Rename duplicate sections 20 Apr 2018 15:27:33 +0200
 469   loc *  exist *  algo *  size *  imp **
 470
 471 - style message about macros inside .Bd -literal and .Dl, in particular
 472   font changing macros like .Cm, .Ar, .Fa (from the mdoclint TODO)
 473
 474 - style message about mismatches between the section number in the
 475   file name (if it is known) and the section number in .Dt
 476   (from the mdoclint TODO)
 477
 478 - style message about NULL without .Dv (from the mdoclint TODO)
 479
 480 - style message about error constants without .Er (from the mdoclint TODO)
 481
 482 - warn when .Sh or .Ss contain other macros
 483   Steffen Nurpmeso, savannah.gnu.org/bugs/index.php?45034
 484   loc *  exist *  algo *  size *  imp **
 485
 486 - style message about violations of the convention
 487   .An name Aq Mt localpart@domain in AUTHORS (from the mdoclint TODO)
 488
 489 - warn about attempts to call non-callable macros
 490   Steffen Nurpmeso  Tue, 11 Nov 2014 22:55:16 +0100
 491   Note that formatting is inconsistent in groff.
 492   .Fn Po prints "Po()", .Ar Sh prints "file ..." and no "Sh".
 493   Relatively hard because the relevant code is scattered
 494   all over mdoc_macro.c and all subtly different.
 495   loc **  exist **  algo **  size **  imp **
 496
 497 - warn about punctuation - e.g. ',' and ';' - at the beginning
 498   of a text line, if it is likely intended to follow the preceding
 499   output without intervening whitespace, in particular after a
 500   macro line (from the mdoclint TODO)
 501
 502 - makewhatis -p complains about language subdirectories:
 503   /usr/local/man//ru: Unknown directory part
 504
 505
 506 ************************************************************************
 507 * documentation issues
 508 ************************************************************************
 509
 510 - mark macros as: page structure domain, manual domain, general text domain
 511   is this useful?
 512
 513 - mention /usr/share/misc/mdoc.template in mdoc(7)?
 514
 515 - Is all the content from http://www.std.com/obi/BSD/doc/usd/28.tbl/tbl
 516   covered in tbl(7)?
 517
 518 ************************************************************************
 519 * performance issues
 520 ************************************************************************
 521
 522 - the PDF file is HUGE: this can be reduced by using relative offsets
 523
 524 ************************************************************************
 525 * structural issues
 526 ************************************************************************
 527
 528 - POSIX says in the documentation of sysconf(3) that PATH_MAX
 529   is allowed to be so large that it is a bad idea to use it
 530   for sizing static buffers.  So use dynamic buffers throughout.
 531   See the file test-PATH_MAX.c for details.
 532   Found by Aaron M. Ucko in the GNU Hurd via Bdale Garbee,
 533   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=829624
 534
 535 - We use the input line number at several places to distinguish
 536   same-line from different-line input.  That plainly doesn't work
 537   with user-defined macros, leading to random breakage.
 538
 539 - Is it possible to further simplify ENDBODY_SPACE?
 540
 541 - Find better ways to prevent endless loops
 542   in roff(7) macro and string expansion.
 543
 544 - make buffers for parsing functions const
 545   christos@ via wiz@  Fri, 18 Dec 2015 17:10:01 +0100
 546
 547 - struct mparse refactoring
 548   Steffen Nurpmeso  Thu, 04 Sep 2014 12:50:00 +0200
 549
 550 ************************************************************************
 551 * CGI issues
 552 ************************************************************************
 553
 554  - Enable HTTP compression by detecting gzip encoding and filtering
 555    output through libz.
 556  - Privilege separation (see OpenSSH).
 557  - Enable caching support via HTTP 304 and If-Modified-Since.
 558
 559 ************************************************************************
 560 * to improve in the groff_mdoc(7) macros
 561 ************************************************************************
 562
 563 - .Cd # arch1, arch2 in section 4 pages:
 564   find better way to indicate multiple architectures, maybe:
 565   allow .Dt vgafb 4 "macppc sparc64"
 566   already shown as "Device Drivers Manual (macppc sparc64)"
 567   for apropos, make that "vgafb(4) - macppc # sparc64" instead of "- all"
 568   groff can be made to show multiple arches, too, but it is
 569   tedious to do the string parsing in roff code...
 570   jmc@ 23 Apr 2018 07:24:52 +0100 [man for vgafb(4)...]
 571   loc **  exist **  algo *  size *  imp ***
 572
 573 - use uname(1) to set doc-default-operating-system at install time
 574   tobimensch  Mon, 1 Dec 2014 00:25:07 +0100
 575
 576 - apostrophe (39), circumflex (94), grave (96), tilde (126)
 577   in manuals: \(aq, \(ha, \`, \(ti
 578   Re: [Groff] ASCII Minus Sign in man Pages.
 579   bentley@ 26 Apr 2017 10:02:06 -0600
 580   Do we need to fix existing manuals?
 581   Do we need to fix the definition of the mdoc(7) language?