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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
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+Date: 14 March 91 Message No: 036
+
+To: TeX implementors and distributors
+
+From: Barbara Beeton
+
+Subject: Messages from DEK, part 1
+
+
+The latest package of marked-up messages from DEK was postmarked
+15 January 92. It contained 10 checks, including two for actual bugs.
+Unfortunately, other matters have conspired to delay my forwarding of
+all this material, and I apologize. (I don't suppose anyone out there
+would like to be a TUGboat production assistant? Or has lots of
+experience in moving from one office to another with less shelf space
+without losing track of anything? Didn't think so, somehow.)
+
+As some of you may know, DEK was awarded an honorary doctorate by the
+Royal Institute of Technology in Stockholm last November. At that time,
+some bug reports and other questions were apparently given to him in
+person, and changes have been delayed as explained in this note which
+accompanied the package:
+
+ Barbara: Many thanks for this compilation! I will not however be
+ ready to update the sources until February because I mistakenly
+ put some things recd in Sweden into the wrong box and they are
+ currently being shipped via _sea_ _mail_.
+ I have gone through this material but will hold off updating the
+ master sources until I've gotten through some other things sent
+ to me in Stockholm from Poland, some of which may be extremely
+ important
+
+I have just finished checking the /tex area at labrea. There are no new
+files in the errata directory, and as these are usually the first to be
+installed, I assume that the main update has not yet been made.
+
+
+########################################################################
+
+Contents:
+ [ part 1 ]
+ >>> responses to DEK Sep 26 package
+ >>> DEK's alpha test, TeX 3.14a
+ >>> TeXbook errata
+ >>> inconsistent ligature/kerning behavior
+ >>> inconsistent expansion of \string, etc.; \newlinechar
+ >>> \halign + box assignment within displays
+ >>> positive/negative xn_over_d, tex.web section 107
+ >>> DRF's "remaining comments"
+ >>> suggestion -- additional tracing facilities for \if*
+ >>> DEK's "local" change files, not at labrea
+ [ part 2 ]
+ >>> glue_ratio overflow
+ >>> \TeX logo; some problems with \loop
+ >>> cedilla accent macro in plain.tex
+ >>> missing \mathsurround in plain.tex
+ >>> \arrowvert code, plain.tex
+ >>> MF -- bugs or features? (also, some ACP errata)
+ >>> MFbook errata
+ >>> WEAVE -- Peter Breitenlohner
+ >>> WEAVE -- Brian {Hamilton Kelly}
+ [ sent separately ]
+ >>> Barry Smith, |history| variable in TeX.WEB
+ >>> Chris Rowley, two items: \fontdimen2 and marks
+
+************************************************************************
+
+>>> responses to DEK Sep 26 package
+
+Date: Mon, 23 Dec 91 13:23:58 +0100
+From: Eberhard Mattes <mattes@azu.informatik.uni-stuttgart.de>
+Subject: Backenfisch, tex.web
+
+> [ dek: should i have used `backenfisch' instead? ]
+
+Maybe deleting `compound' on p. 96 would be better since I have found
+no word with ck hyphenated k-k *because* it is a compound word.
+(Of course there are words containing tt hyphenated tt-t *because*
+they are compound words.)
+
+ [ dek:
+ point well taken ... but I wasn't serious and i _did_ delete
+ `compound' in September as he requested
+ ]
+ ---
+
+In tex.web, there's a @^system dependencies@> missing for the line
+ [ dek: \S798 ]
+
+if n>max_quarterword then confusion("256 spans"); {this can happen, but won't}
+ ^^^
+ This is system-dependent.
+ [ dek: $2.56 ]
+
+Yours,
+ Eberhard Mattes (mattes@azu.informatik.uni-stuttgart.de)
+
+<<< end responses to DEK Sep 26 package
+
+************************************************************************
+
+>>> DEK's alpha test, TeX 3.14a
+
+Date: Tue 24 Sep 91 11:22:21-EST
+From: bbeeton <BNB@MATH.AMS.COM>
+To: cet1%phx.cam.ac.uk@nsfnet-relay.ac.uk,
+ tex%uk.ac.cranfield.rmcs@nsfnet-relay.ac.uk, pzf5hz@ruipc1e.Bitnet
+Subject: message from dek -- tex alpha version 3.14a
+
+chris, brian, and frank,
+you are hereby deputized to follow dek's instructions and test out
+the new version. [ ... ]
+i won't forward this information to anyone else [for at least two
+weeks], and you probably should be discreet about it too. thanks.
+cheers. -- bb
+ --------------------
+Date: Fri, 20 Sep 91 12:50:54 -0700
+Subject: note from Don
+
+ [ copy of message from dek ]
+ -------
+Date: Thu, 26 SEP 91 22:31:01 BST
+From: TEX@rmcs.cranfield.ac.uk
+Reply-to: Brian {Hamilton Kelly} <TeX@rmcs.cranfield.ac.uk>
+Subject: RE: message from dek -- tex alpha version 3.14a
+
+In message <685725741.0.BNB@MATH.AMS.COM>
+of Tue 24 Sep 91 11:22:21-EST, bbeeton <BNB@com.AMS.MATH> wrote:
+
+> chris, brian, and frank,
+> you are hereby deputized to follow dek's instructions ...
+> ... (i will take care of the envelope of "comments and checks"
+ ^
+ (Would I spell this cheques? :-)
+> as soon as i can after i get back to providence.)
+
+Well, I've collected the new files (I *love* the README!!), modified my
+change file to accommodate the new banner and a few of the
+|slow_print|s, and built 3.14a. It's great!! Fixes my problem with
+hyphenation vs. boundary ligatures perfectly. And what an elegant
+solution: I'd expected the fix to be complicated, but it just requires
+one simple global and the odd preservation of context.
+
+> Date: Fri, 20 Sep 91 12:50:54 -0700
+> Subject: note from Don
+>
+> Meanwhile, there's some more "immediate" news. I've prepared an
+> alpha-test version of TeX, called version 3.14a. Before I release
+> it officially, I'd like CET1 and Brian Hamilton-Kelly and maybe
+> Frank Mittelbach [and anybody else you think best, but I don't really
+> want this version to proliferate] to try it. There are two changes,
+> one to cure the anomaly Frank noticed about \newlinechar acting
+> differently wrt \write and \message [and other similar glitches I
+> then noticed myself], the other to fix I hope the problem Brian was
+> having with Greek. I'm reluctant to let the version number converge to
+> \pi too quickly, so I would at least like to have Brian accumulate
+> some experience with his Greek tests before putting this out widely.
+> Of course anybody is free to use it at their own risk.
+
+Be warned, however, that so far I've only tested it against the input
+that caused me problems back in April. I'll try to do some more
+thorough testing in the near future.
+
+ [ dek:
+ Certainly hope you did by now -- I need more reassurance than
+ a single test
+ ]
+
+> The files tex.web and tex82.bug have been moved to labrea.stanford.edu
+> where they are accessible via anonymous ftp. After logging in,
+> connect to directory alpha (which is for alpha-test software).
+> I forgot to copy the trip test files; if they are desperately needed,
+> I could bring them in from home.
+
+I haven't TRIPped the new TeX for this reason. The interesting thing
+would be if TRIP were extended to check the new ligature/hyphenation
+code: I expect that, with DEK's customary thoroughness, he'll have done
+this, so look forward to applying the tests myself when 3.14a emerges as
+3.141.
+
+ [ dek:
+ Actually my customary thoroughness is becoming less customary
+ ]
+
+> So, next week you'll get my letter explaining all! Meanwhile, a
+> lookahead: I'll be in Sweden during November and December (thanks to
+> some good words from Roswitha, I'll getting an honorary degree
+> there!), and I plan to make the next official update to TeX sources
+> early in January. By then, this version 3.14a should be checked out,
+> and I can release it as version 3.141.
+
+Whilst you're talking to DEK, barbara, what response did he give to that
+d..d problem of Weave failing to wrap correctly when processing a TeX
+comment? I have a horrible suspicion in my mind that he's already said
+something to the effect that he edited it manually! Or am I imagining
+that horror? My fix works very well and doesn't have any bugs that I
+can see, so why doesn't he adopt it?
+
+Brian HK
+ -------
+Date: Sun, 29 Sep 91 00:56:57 BST
+From: Chris Thompson <CET1@phoenix.cambridge.ac.uk>
+To: Barbara Beeton <BNB@MATH.AMS.com>
+Cc: Brian {Hamilton Kelly} <tex@rmcs.cranfield.ac.uk>,
+ Frank Mittelbach <pzf5hz@ruipc1e.bitnet>
+Subject: Re: [message from dek -- tex alpha version 3.14a]
+
+Barbara, Brian, Frank,
+
+ I have fetched and compiled TeX 3.14a. Unfortunately, change 397
+seems to have bugs. Try the following input:
+
+ % TeX 3.14a test
+ \pretolerance=-1
+ \ Respectively.\par
+ \showboxbreadth=255 \showboxdepth=255 \showlists
+ \bye
+
+and compare the log files for 3.14 and 3.14a. That for 3.14a has an
+extra kern in between the "-ly" and the ".":
+
+ .\tenrm e
+ .\tenrm l
+ .\tenrm y
+ .\kern-0.83334 \ This kern has been doubled by the
+ .\kern-0.83334 / automatic hyphentaion algorithm.
+ .\tenrm .
+ .\penalty 10000
+
+ [ dek:
+ well, this made me feel very sick, but I sure am thankful to
+ Chris for finding it.
+ $10.24
+ ]
+
+I discovered this while checking that 'webman.tex' generated the same
+DVI file (except for date stamp), which is part of my standard paranoia
+suite. There were two discrepancies of the above type in the very first
+paragraph... but the rest of the document produced no more!
+
+ [ dek:
+ I think probably the _old_ 3.0 would also produce double kerns
+ in cases where kern was specified before right boundary character
+ by font designer [e.g. to kern after f at end of word]
+
+ While studying this I found another mistake in my code from
+ September. But I think the basic idea was sound, only the
+ execution was faulty.
+
+ Still I guess I should try another alpha test with "3.14b"?
+ ]
+
+Brian & Frank: can you confirm this effect?
+
+Chris Thompson
+Cambridge University Computing Service
+JANET: cet1@uk.ac.cam.phx
+Internet: cet1@phx.cam.ac.uk
+ -------
+Date: Mon, 30 SEP 91 15:46:17 BST
+Reply-to: Brian {Hamilton Kelly} <TeX@rmcs.cranfield.ac.uk>
+From: TEX@rmcs.cranfield.ac.uk
+Subject: Re: [message from dek -- tex alpha version 3.14a]
+
+In message <A4912BE187A67A40@UK.AC.CAMBRIDGE.PHOENIX> of Sun, 29 Sep 91
+00:56:57 BST, Chris Thompson <CET1@UK.AC.CAMBRIDGE.PHOENIX> wrote:
+
+> Barbara, Brian, Frank,
+>
+> I have fetched and compiled TeX 3.14a. Unfortunately, change 397
+> seems to have bugs. [ ... ]
+>
+> and compare the log files for 3.14 and 3.14a. That for 3.14a has an
+> extra kern in between the "-ly" and the ".":
+>
+> .\tenrm e
+> .\tenrm l
+> .\tenrm y
+> .\kern-0.83334 \ This kern has been doubled by the
+> .\kern-0.83334 / automatic hyphentaion algorithm.
+> .\tenrm .
+> .\penalty 10000
+>
+> [ ... ]
+>
+> Brian & Frank: can you confirm this effect?
+
+I have repeated Chris' experiment, and can confirm that 3.14a does
+indeed double the kern. Oh dear...
+
+The odd thing is that I compared the outputs resulting from running
+DVItype on the DVI outputs of my Greek test, and saw only the expected
+change from medial sigma to terminal sigma (with relevant horizontal
+positioning changes). But I may have missed other horizontal changes
+due to this bug: I've thrown the printout away again by now,
+unfortunately!
+
+Brian
+
+<<< end DEK's alpha test, TeX 3.14a
+
+************************************************************************
+
+>>> TeXbook errata
+
+Date: Tue, 19 Nov 91 16:05:02 GMT
+From: Chris Thompson <CET1@phoenix.cambridge.ac.uk>
+Subject: TeXbook p.178 bug report
+
+ Here is another TeXbook bugette report by Robert Hunt. I suppose it is
+right in theory, unless it comes under the "deliberate lie" clause. Anyway,
+perhaps you would like to have someone else vet it: I am getting to the stage
+with Robert's bug reports that I just wish he would shut up! He seems happy
+with the latest p.377 fix, by the way.
+
+ -----------------------------------------------------------------------
+REH10 15 Nov 1991 16.49
+Very minor mistake on p.178 of the TeXbook: it claims that using \phantom{...}
+in a maths formula always produces the same spacing (vertical and horizontal)
+as just {...}; but of course this isn't true as \phantom can't tell whether the
+current maths style is cramped or not, so \phantom{U^2} will produce different
+vertical spacing in cramped style compared with what {U^2} would produce. I
+don't think this is particularly worth worrying about, but it's always annoyed
+me that \mathchoice doesn't distinguish between (say) T and T'.
+ -----------------------------------------------------------------------
+
+ [ dek:
+ $2.56
+ I'm going to put the apology on page 360 because the truth would
+ interfere with the exposition on p 178
+ ]
+
+Chris Thompson
+
+ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+Date: Tue, 3 Dec 91 15:13:01 MST
+From: Nelson H. F. Beebe <beebe@math.utah.edu>
+Subject: Possible bug in TeXbook, p.270
+
+Last night, while studying to TeXbook to better understand TeX's rules
+for when spaces are significant, I found what I believe is a small
+error in the TeXbook. I checked errata files errata.one .. errata.six
+without finding this error already logged.
+
+The TeXbook, p.270, gives BNF rules for the grammar of dimensions.
+>From this grammar, one concludes from the rules (pulled from
+texman.tex)
+
+<optional {\tt true}>\is[true]\alt<empty>
+
+<unit of measure>\is<optional spaces><internal unit>
+ \alt<optional {\tt true}><physical unit><one optional space>
+
+<normal dimen>\is<internal dimen>\alt<factor><unit of measure>
+
+<factor>\is<normal integer>\alt<decimal constant>
+
+<decimal constant>\is|.|$_{12}$\alt|,|$_{12}$
+ \alt<digit><decimal constant>
+ \alt<decimal constant><digit>
+
+that "123 truept" is illegal input, since no space may precede the
+word true according to the grammar.
+
+Nevertheless, TeX the program happily accepts such space:
+
+This is TeX, C Version 3.14
+**\relax
+
+*\dimen0 = 12345 true pt
+
+ [ dek:
+ see the \P on p 268 that begins `We shall use a special
+ convention for keywords'. _true_ is a keyword
+ ]
+
+*\showthe\dimen0
+> 12345.0pt.
+<*> \showthe\dimen0
+
+?
+
+I believe that TeX the program is correct, and is consistent with its
+permitting optional space before non-true dimensions.
+
+This suggests that the TeXbook should have the rule
+
+<unit of measure>\is<optional spaces><internal unit>
+ \alt<optional {\tt true}><physical unit><one optional space>
+
+changed to
+
+<unit of measure>\is<optional spaces><internal unit>
+ \alt<optional spaces><optional {\tt true}><physical unit><one optional space>
+
+I'm assuming that AB|CDE is to be parsed as (AB)|(CDE) (the
+conventional interpretation in BNF grammars), rather than A(B|C)DE;
+the latter would not make sense here anyway.
+
+========================================================================
+Nelson H.F. Beebe
+Center for Scientific Computing
+Department of Mathematics
+220 South Physics Building
+University of Utah
+Salt Lake City, UT 84112
+USA
+ Tel: (801) 581-5254
+ FAX: (801) 581-4148
+ Internet: beebe@math.utah.edu
+========================================================================
+
+<<< end TeXbook errata
+
+************************************************************************
+
+>>> inconsistent ligature/kerning behavior
+
+Date: Wed, 25 Sep 91 13:13:55 +0200
+From: Bernd Raichle <raichle@azu.informatik.uni-stuttgart.de>
+Subject: Bug in TeX's ligature builder?! (No, it's documented.)
+
+In a letter to DEK in November 1989 (i.e., before TeX 3.0; appeared in
+TeXhax 90, Issue 5) Frank Mittelbach summarized some requirements of a
+new TeX version. For example, he mentioned manipulations of the
+"Ligatures and kerning tables" and the need to "Reconsider paragraphs
+after page-breaking". Other users had and have similar wishes and
+requirements.
+
+But nobody mentioned a bug, or better --- because this "bug" is
+documented in the TeXbook --- the inconsistent and (for the beginner)
+mysterious behaviour when TeX builds ligatures and inserts kerning.
+
+Try the following in plain TeX and look at the output. I have used
+the fl-ligature as an example. (TeX's behaviour for kerning between
+two characters is exactly the same.)
+
+ ------------------------------ CUT ------------------------------
+\hsize=5cm % linebreak for more than three words
+\hyphenation{Au-flage}% for demonstration (correct german is Auf-la-ge)
+
+Auflage\par % (1) show `fl' ligature
+Auf{}lage Auf\relax lage\par % (2) simple way to avoid the ligature
+
+\pretolerance=10000 % no second pass
+Auf{}lage
+Auf{}lage Auf{}lage Auf{}lage Auf{}lage\par % (3) no ligatures
+
+\pretolerance=-1 % force second pass
+Auf{}lage % no(!) ligature, because there's no preceding glue
+Auf{}lage Auf{}lage Auf{}lage Auf{}lage\par % (4) ligatures
+
+Auf{}lage % (5) no(!) ligature, there's no preceding glue
+Auf\kern0pt lage % no lig, explicit kern
+Auf\/lage % no lig, explicit kern
+$\rm Auflage$ % example of ligature in math mode
+$\rm Auf{}lage$ % no lig, in math mode
+\hbox{Auf{}lage} % no lig, in packed hbox
+Auf{}lage\vrule width0pt\ % no lig, followed by a rule node
+Auf{}lage\kern0ptAuf{}lage % 1st ligature, 2nd no ligature
+Auf{}lage\par % ligature
+\bye
+ ------------------------------ CUT ------------------------------
+
+Example (1) shows the normal fl ligature, in example (2) I suppress
+the ligature with an empty group (see TeXbook, exercise 5.1 and
+answer) or a \relax (both are non-character tokens).
+
+In example (3) I use empty groups to suppress the ligatures. The
+same(!) input paragraph in example (4) contains ligatures. The only
+and very important difference between (3) and (4) is the value of
+\pretolerance. (Note that the first word in (4) has no fl-ligature!)
+
+Example (5) gives a quick overview of TeX's behaviour, when the same
+word (= the same input!) is used in a different context. You can
+think of other examples: hbox the word... and unhbox it. Try the same
+with the ''-ligature (i.e. compare '' with '{}'), etc.
+
+
+Very short explanation of this behaviour: when TeX is in hmode,
+ligatures and kernings are build out of the (current input) token
+list. Non-character tokens (like { or \relax) influence ligatures and
+kerning.
+
+When TeX is in math mode or after hyphenation is done in the second
+pass of the line_break algorithm, ligatures and kernings are build out
+of the node list representing the current paragraph (or math list).
+This node list doesn't contain representations for tokens like { or
+\relax anymore. Because not all parts of the node list are tried for
+hyphenation, not all of the supressed ligatures are reconstituted.
+
+
+TeX has a powerful linebreak algorithm, a powerful hyphenation
+capability and powerful ligature and kerning tables.
+But the connection between them shows IMHO design bugs, if you want to
+use them and expect the same output from the same input.
+
+ [ dek:
+ This is unfortunate but known and I decided long ago that
+ the cure would be worse than the disease.
+ ]
+
+Comments, etc. ...?? (... are expected!!)
+
+ -bernd
+
+PS: I have ideas how to make ligatures/kerning more consistent.
+ But the result, after the necessary changes (in a few places)
+ are applied, is a "TeX" which fails the Trip-Test.
+
+ __________________________________________________________________________
+ Bernd Raichle, Student der Universit"at Stuttgart | "Le langage est source
+ privat: Stettener Str. 73, D-W-7300 Esslingen | de malentendus"
+ email: raichle@azu.informatik.uni-stuttgart.de | (A. de Saint-Exupery)
+
+<<< end inconsistent ligature/kerning behavior
+
+
+########################################################################
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% Character code reference
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%
+% Upper case letters: ABCDEFGHIJKLMNOPQRSTUVWXYZ
+% Lower case letters: abcdefghijklmnopqrstuvwxyz
+% Digits: 0123456789
+% Square, curly, angle braces, parentheses: [] {} <> ()
+% Backslash, slash, vertical bar: \ / |
+% Punctuation: . ? ! , : ;
+% Underscore, hyphen, equals sign: _ - =
+% Quotes--right left double: ' ` "
+%"at", "number" "dollar", "percent", "and": @ # $ % &
+% "hat", "star", "plus", "tilde": ^ * + ~
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+[ end of message 036 ]
+