========================================================================
Date:         Mon, 10 Oct 1994 18:05:48 +0100
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: "J%org Knappen, Mainz" <KNAPPEN@VKPMZD.KPH.UNI-MAINZ.DE>
Subject:      FAQ: Differences to the last edition

************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
    3   Fourth edition
    4   Date: 10-OCT-1994
    5   Currently maintained by: knappen@vkpmzd.kph.uni-mainz.de (J%org Knappen)
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
    3   Third edition
    4   Date: 26-JAN-1994
    5   Currently maintained by: knappen@vkpmzd.kph.uni-mainz.de (J%org Knappen)
************
************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
   24   under tex/info/tex-implementors. In addition, I recommend reading the
 list
   25   of TeX bugs (tex-archive/systems/knuth/errata/tex82.bug).
   26
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
   24   under tex/info/tex-implementors.
   25
************
************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
   61   8. Additions to the TeX kit
   62   8.1. dvicopy
   63   8.2. dvitodpl and dpltodvi
   64   8.3. gftotxt
   65   8.4. qdtexvpl
   66   8.5. fontinst
   67   8.6. afmtotfm
   68   9. Existing extensions to TeX
   69   9.1. TeX-XeT
   70   9.2. TeX--XeT
   71   9.3. MLTeX
   72   9.4. SiSiSi
   73
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
   60
************
************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
   90     As of September 1994, there are two activities going on, the ETeX
 group
   91     is working on a extension of TeX and is going to produce a first ETeX
 soon.
   92     The NTS group takes the path to reimplement TeX in common LISP to get
   93     a deeper understanding of how the modules of TeX are cooperating which
   94     eachother.
   95
   96     Independently, the Omega project was launched to produce a typesetting
 system
   97     which uses unicode as internal code and can handle arbitrarily encoded
 input
   98     via filters.
   99
  100     The beforementioned projects were presented at the 1994 TUG meeting at
 Santa
  101     Barbara and at the EuroTeX'94 conference at Gdansk. For more
 information,
  102     consult the respective proceedings. For the Omega project exists a
 mailing
  103     list, omega@ens.fr. To subscribe, send an e-mail to LISTSERV@ens.fr.
  104
  105   1. Proposed features of a New Typesetting system
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
   77   1. Proposed features of a New Typesetting system
************
************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
  166     (one hyphen only). Allthough TeX will be frozen at version $\pi$,
  167     this is not true for TeX--XeT. (see also 9.2)
  168
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
  138     (one hyphen only).
  139     Allthough TeX will be frozen at version $\pi$, this is not true for
 TeX--XeT.
  140
************
************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
  390    \afterfi should be expandable, because \if...\fi is expandable.
  391
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
  362    (IMHO the \afterfi should be expandable, because \if...\fi is
 expandable.)
  363
************
************
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;18
  734   8. Additions to the TeX kit
  735
  736   8.0. General
  737     The TeX kit, meaning the bundle of programmes building up a complete
 TeX
  738     installation, contains besides the major programmes TeX and METAFONT
  739     additional programmes, traditionally divided into several groups:
  740
  741     a) TeXware: dvitype, tftopl, pltotf, pooltype, pktype, patgen, vftovp,
  742        vptovf, (outdated: pxtopk, pktopx)
  743     b) MFware: mft, gftodvi, gftopk, (outdated: gftopxl)
  744     c) webware: weave, tangle
  745
  746     And, of course, drivers for the screens and printers.
  747
  748     Other utility programmes more loosely associated with TeX are indexers
  749     (makeindex, idxtex, glotex, ...) and bibliography tools (bibtex,
  750     bibclean, ...). Makeindex and Bibtex are standard tools, because they
  751     are described in the LaTeX manuals.
  752
  753   8.1. dvicopy
  754     Written in WEB by Peter Breitenlohner
  755     Available from CTAN
  756     Resolves all references to virtual fonts in a dvi file. Can be used to
  757     create a dvi file without virtual fonts (e.g. for drivers which cannot
  758     handle vf's).
  759
  760   8.2. dvitodpl and dpltodvi
  761     Written in C by Geoffrey Tobin
  762     Available ?
  763     dvitodpl makes a human readable file from a dvi file. The companion
  764     programme dpltodvi makes a dvi file frome a dvi property list file.
  765     It allows you to change dvi files with a text editor.
  766
  767   8.3. gftotxt
  768     Written in C by Yannis Haralambous
  769     Available ?
  770     Extracts a certain kind of specials from the gf file into a text file.
  771     Workaround for the famous non-ability of METAFONT to write auxiliary
  772     files.
  773
  774   8.4. qdtexvpl
  775     Written by Eberhard Mattes
  776     Part of the emtex distribution (CTAN)
  777     Generates a virtual font from TeX macros. qd = quick and dirty.
  778
  779   8.5. fontinst
  780     Written in TeX by Alan Jeffrey
  781     Available form CTAN
  782     Makes virtual fonts from afm files (PostScript fonts). Used by the
 LaTeX
  783     team to create virtual fonts and fd files for LaTeX2e.
  784
  785   8.6. afmtotfm
  786     Written in C by Thomas Rokicki
  787     Available from CTAN (part of dvips distribution)
  788     Makes tfm files from afm files.
  789
  790
  791   9. Existing extensions to TeX
  792
  793   9.0 General
  794     Here I include short description of existing extensions to TeX. This
 section
  795     does not include commercial TeX implementations because of lack of
 solid
  796     enough information on them. It also does not yet include ETeX, NTS,
 nor
  797     Omega.
  798
  799   9.1. TeX-XeT (Don Knuth and Pierre MacKay)
  800     CTAN: tex-archive/systems/knuth
  801     Adds new primitives \beginR, \endR, \beginL, and \endL for right to
 left
  802     typesetting. Despite their names, the new primitives are insensitive
 to
  803     TeX's grouping mechanism. Outputs a special file in dvi-ivd format,
 which
  804     need be resolved by another programme or requires special drivers.
  805
  806   9.2. TeX--XeT (Peter Breitenlohner)
  807     Available from CTAN  tex-archive/systems/knuth/tex--xet
  808     Implements the same primitives as TeX-XeT, but outputs a normal dvi
 file.
  809     Passes the trip test (as far as I know).
  810
  811   9.3. MLTeX (Michael Ferguson)
  812     Available from  aldebaran.ee.mcgill.ca in pub/mltex
  813     Adds a primitive \charsubdef, which allows the following: input of
 8-bit
  814     characters, participation of accented characters not present in the
 output
  815     encoding in hyphenation, ligatures and kerning with accented letters.
  816     Especially popular in francophone countries.
  817     emTeX supports MLTeX via the /ml option.
  818
  819   9.4. SiSiSi (Wilhelm Barth, Heinrich Nirschl, Heini Hofstaedter und
 Harald
  820                  Mueller)
  821     Available from CTAN: tex-archive/systems/vms (sic!)
  822     Implements another hyphenation algorithm (the name means SIchere
  823     SInnentsprechende SIlbentrennung, which is translated `secure
 sensitive
  824     hyphenation') specific to the german language (with Haupt- und
  825     Nebentrennstellen). Fails the trip test, therefore not a legitimate
 TeX.
  826     In use at TU Wien (Austria).
  827
  828   The End.
******
File $DISK2:[KNAPPEN.NTS]FAQ.TXT;16
  706   The End.
************

Number of difference sections found: 7
Number of difference records found: 128

DIFFERENCES /IGNORE=()/MERGED=1/OUTPUT=$DISK2:[KNAPPEN.NTS]FAQ.DIFF;1-
    $DISK2:[KNAPPEN.NTS]FAQ.TXT;18-
    $DISK2:[KNAPPEN.NTS]FAQ.TXT;16

========================================================================
Date:         Mon, 10 Oct 1994 18:03:48 +0100
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: "J%org Knappen, Mainz" <KNAPPEN@VKPMZD.KPH.UNI-MAINZ.DE>
Subject:      Frequently asked questions -- 4th edition

    Frequently Asked Questions of NTS-L

Fourth edition
Date: 10-OCT-1994
Currently maintained by: knappen@vkpmzd.kph.uni-mainz.de (J%org Knappen)

Remark about the format:

This faq is divided into several sections and subsections. Each section
contains a subsection general with some ideas which have not yet been
discussed. I added a date to some subsections to allow you to retrieve
fuller discussions from the archives. The transactions of this group are
archived on

        ftp.th-darmstadt.de    [130.83.55.75] *)
        directory pub/tex/documentation/nts-l

Each file in this directory is named yymm, where (guess :-) yy is the
year and mm is the month when the mail arrived. (I.e., all postings
of one month are bundled in one file.)
*) Avoid using the number above ... it is subject to changes.

Related stuff which is very worth reading you can find on the CTAN archives
under tex/info/tex-implementors. In addition, I recommend reading the list
of TeX bugs (tex-archive/systems/knuth/errata/tex82.bug).

-1. Contents

0. About NTS
1. Proposed features of a New Typesetting system
1.1. Improvement of Quality
1.2. Internationality
1.3. New Look and Feel
1.4. Changing the ligaturing algorithm
2. Proposed additions to TeX (concrete new primitives)
2.1. \lastmark etc.
2.2. \system
2.3. \skylineskiplimit, \skylinehorizontallimit
2.4. \directioncode
2.5. \textcode
2.6. \afterfi
2.7. \interactionmode
2.8. \mathspacing
2.9. \inputescapechar
2.10. \middle
2.11. \outputunit
3. Metaremarks
3.1. TeX is not perfect
3.2. In which language shall NTS be written
3.3. The TeX language
3.4. The TeX engine
4. Deviations
4.1. Automated Kerning
4.2. About Lout
5. Proposed changes to METAFONT
5.1. Writing to auxiliary files
6. Proposed changes to the tfm file format
6.1. Vertical kerning
6.2. Cross-font ligatures
7. Proposed changes to the dvi file format
8. Additions to the TeX kit
8.1. dvicopy
8.2. dvitodpl and dpltodvi
8.3. gftotxt
8.4. qdtexvpl
8.5. fontinst
8.6. afmtotfm
9. Existing extensions to TeX
9.1. TeX-XeT
9.2. TeX--XeT
9.3. MLTeX
9.4. SiSiSi

0. About NTS (Mar 93, see also Jul 92)

  At DANTE '93, held at the Technical University Chemnitz last week, Joachim
  Lammarsch, President of Dante, announced that the NTS project which had been
  started under the aegis of DANTE, was to be re-formed under a new
  co-ordinator, Philip Taylor. The old core group, announced at the previous
  annual DANTE meeting, was to be dissolved, and a new core group established.
  Membership of the new core group will not be restricted to DANTE members,
  but will instead be offered to various well-known names (and some
  lesser-known!) in the international TeX community.

  see also:
  F. Mittelbach: E-TeX Guidelines for future TeX, TUGboat v11n3 (1990)
  P. Taylor: The future of TeX, EuroTeX'92 Prag (Proceedings); reprinted
  in TUGboat v13n4, 433 (1992)

  As of September 1994, there are two activities going on, the ETeX group
  is working on a extension of TeX and is going to produce a first ETeX soon.
  The NTS group takes the path to reimplement TeX in common LISP to get
  a deeper understanding of how the modules of TeX are cooperating which
  eachother.

  Independently, the Omega project was launched to produce a typesetting system
  which uses unicode as internal code and can handle arbitrarily encoded input
  via filters.

  The beforementioned projects were presented at the 1994 TUG meeting at Santa
  Barbara and at the EuroTeX'94 conference at Gdansk. For more information,
  consult the respective proceedings. For the Omega project exists a mailing
  list, omega@ens.fr. To subscribe, send an e-mail to LISTSERV@ens.fr.

1. Proposed features of a New Typesetting system

1.1. Improvement of Quality

1.1.0 General:
  Optimised page breaking, avoiding ``rivers'', letterspacing (see also 4.1),
  Hyphenation (Haupt- und Nebentrennstellen), grid typesetting

1.1.1 Skyline approach to line breaking (Mar 93)

You can break paragraphs as usual with the current model, where all
lines are simple rectangular boxes.  If there's no necessity to insert
\lineskip, then you don't have to look at the skyline.  Only if two
lines are too near (e.g. distance<\lineskiplimit), you have to look
into the two rectangular boxes and to check if the boxes inside
overlap at one or more places.
For the worst case (i.e., you have to look at the skyline for all
pairs of lines) processing the skyline model consumes a lot of process
time, but this shouldn't hinder us to test this idea and look at the
results.

Btw, the skyline model seems to be easy to implement in the current
TeX, because we need only some changes when the finally broken lines
of the paragraph are put on the vertical list.  There are more changes
needed in the code, if the line break should be changed for the cases
where it is possible to avoid an overlap with other break points, but
IMHO it's nonetheless a relatively small change.

Additionally you have to introduce some new parameters.  I think of
something like:
        \skylineskiplimit    (b)
                minimum vertical distance between two boxes
        \skylinehorizontallimit   (a)
                minimum horizontal distance


line 1:       ------------
        :     :
        :     :             ----------
        ------- <== (a) ==> :        :
           ^                :        :
          (b)               :        -------
           v                :
       ----------------------
line 2:

and other parameters, but the necessary parameter set, realization,
etc. for "skylines" are subject of discussion.


1.2. Internationality

1.2.0 General:
  Typesetting in arbitrary directions, unicode support (16bits), ISO10646
  support (32bits), ligatures pointing to other fonts, vertical kerning,
  better accent handling (\topaccent and \botaccent)

1.2.1 Supporting TeX--XeT primitives for right to left typesetting
  TeX--XeT is an existing extension to TeX supporting right-to-left
  typesetting an producing a usual dvi-file. TeX--XeT is written by
  P. Breitenlohner and freely available. It is different from TeX-XeT
  (one hyphen only). Allthough TeX will be frozen at version $\pi$,
  this is not true for TeX--XeT. (see also 9.2)

1.3. New Look and Feel

1.3.0 General
  Windows support, wysiwyg-like features

1.3.1 Interaction with the operating system and other programmes
  see 2.2. \system

1.4. Changing the ligaturing algorithm
  Replace the (IMHO over-)optimized ligature builder/kerning routines in
  TeX by routines which separate between the building of ligatures and
  the insertion of kerns between the characters/ligatures.

  This can be realized in a simple way by using two passes: in the
  first pass the ligatures are built and in the second pass the
  resulting ligatures and remaining single characters are used to
  determine the necessary kerns.

  To ensure compatibility between e-TeX and TeX, it will be possible to
  switch between the new and the current behaviour.

  Additionally a flag in the TFM file of each font can be used to
  specify which behaviour is to be used for the font.  This ensures that
  "old" fonts with some tricky ligature/kerning programs depending on
  the old behaviour can still be used with e-TeX.  (I don't know if this
  font dependent switching is really necessary.  Comments, please!!)

  Example:

  A font contains the following ligatures and kerns:

        o "             => ligature (o")  (= \"{o})
        V o             => kern(-smallkern)
        V lig(o")       => nothing

  Input:        V o "
  Output of current TeX:        V kern(-smallkern) ligature(o")
  Output with change:           V                  ligature(o")

  Status:

  Bernd Raichle has written a simple, but running reimplementation of TeX's
  ligature/kerning routine (in CommonLisp), which still waits to be
  rewritten as a TeX.web change file.
  The ligature builder/kerning routine is realized in one pass; kerns
  are introduced in a delayed manner, i.e., after we are sure that
  there's no possibility for a ligature.
  Additionally there's a switch between the current TeX and the new
  behaviour.  (The TRIP test fails with the new behaviour.)

PS: IMHO the ligature/kerning routines should be further changed to
  remove the `shelf{}ful' anomaly (see TeXbook, exercise 5.1), i.e.,
  reinserting ligatures when words are hyphenated.
  The change should allow ligatures for inputs like `f{}f' or
  `f\relax f', which will simplify the macros in `german.sty',
  Babel and changed macros for \", \', ... which are used to select
  characters from DC fonts or other fonts with national characters.

2. Proposed additions to TeX (concrete new primitives)

2.0. General (Jun 92, Jul 92, Aug 93)
  A rather long list of proposed primitives (more or less worked out) was
  posted by Karl Berry on 10-Jun-1992. It contains suggestions like:
  \elseif (selfexplaining), \format{foo} (allow the author to select a format),
  \host{name} \host{os} \host{type} \getenv to extract host information
  \TeXversion, \usertime, \everyeof, and others.

  It is currently not possible to get some information about the current
  mode of TeX and make conditionals dependent on it and/or restore it after
  some action (see 2.7. \interactionmode)

  More of this kind are a conditional or primitive to signal, when TeX is
  in "expand only" mode (\edef, \mark, \write, ...), when TeX is
  scanning numbers (here I'm thinking---and hating---german.sty's active
  doublequote, which can also be used as a marker for hexadecimal
  numbers), when TeX is peeking for some special tokens (first column in
  an \halign), etc...

2.1. \lastmark etc. (Jun 92, Jul 92)
  Currently you cannot remove a \write or \mark or
  \insert or rule from any list at all. If we allow them to removed, how
  will the commands appear to the user? If we have \lastmark like
  \lastbox, then perhaps we need a mark data type so that we can say something
  like \setmark0=\lastmark. It will probably be difficult
  in the case of \insert's to think of a good command syntax.

  Perhaps \lastpenalty, \lastkern, \lastskip should
  remove the penalty, kern, skip, ... so that they are consistent with
  \lastbox. Then \unpenalty, \unkern, and \unskip would be unnecessary.
  (Of course most macro packages would probably want to reimplement them,
  as macros: \def\unpenalty{\count@\lastpenalty},
  \def\unkern{\dimen@\lastkern}, \def\unskip{\skip@\lastskip}.)

2.2. \system (Mar 93)

2.2.0 General
  Oops, this got rather longish, but this topic has caused plenty of traffic.
  I decided to quote directly the positions of both sides. The subpoints are
  1. Pro 2. Contra 3. Syntax

2.2.1 Pro
  First comes the proposal as formulated by Phil Taylor:

  There has been much discussion on how a \system primitive might interact
  with different operating systems, each with different functionality and a
  different syntax.  My idea was to extend the concept of a `TeX
  implementation', which at the moment implies the creation and application
  of a change-file to the master TeX source, to include an implementation-
  specific macro library.  Thus each implementor, as well as creating and
  applying a change file, would also be responsible for mapping a well-defined
  set of macros, through the \system primitive, to the syntax and
  functionality of the operating system for which he or she has assumed
  responsibility.  To cite a specific example:

  Assume that in e-Lib (a hypothetical macro library to accompany e-TeX),
  a macro \sys$delete_file {<parameters>} is partially defined; then each
  implementor would be responsible for mapping \sys$delete_file {<parameters}>
  to his or her own implementation of \system.  e-Lib would define the effect
  and the result(s), \system would provide the interface, and the implementor
  would be responsible for providing the mapping.

  The question has been asked: ``Why via \system and macros?  Why not via
  explicit primitives to carry out the various functions that are envisaged?''

  To which I would suggest that the answer is ``Because `the various functions
  which are envisaged' is both enormous (requiring many new primitives), and
  yet not large enough (because no matter what functionality we posit, someone
  will come up with an idea that has not been considered).''  By implementing
  just one \system primitive, and an extensible e-Lib macro library, one can
  create a robust and well-tested e-TeX whilst allowing new system interactions
  to be added at the simplest points: through the implementation-independent
  and implementation-specific components of e-Lib.

2.2.2 Contra
  And here's from the ``Minority Report'' (Tim Murphy and J"org Knappen)

  May I recall the immortal words of Ken Thompson,
  "A program should do one thing, and do it well." (TM)

  I don't like the hackers to decide, making eTeX yet another programme from
  which I can send e-mail and read news :-) Maybe people will tell me eTeX is
  a fine operating system, but TeX version $\pi$ is the better typesetter :-)

  But there is another side of \system, I want to call it the monstrosity
  side. Many people are thinking now, that TeX is a monster and difficult to
  tame. \system will add to this monstrosity. It will create a new paradise
  for hackers creating system hacks. And it will make people turn away from
  eTeX and use other products, even if they are far less secure. (JK)

2.2.3 Syntax
  If a \system command is required, should it not have a similar syntax
  and semantics to the a similar TeX command.  I can't think of anything
  else in TeX (prepares to be shown wrong) that expands in the mouth and
  has side-effects.  Should it not be like \read, \write etc. that is it
  generates a whatsit that is obeyed at shipout, unless preceded by an
  \immediate, in which case it is done immediately by the stomach.
  There seem to be two obvious syntaxes, one like \write:
     \system{foo}  or  \immediate\system{foo}
  and one like \read:
     \system{foo} to \baz  or  \immediate\system{foo} to \baz
  The latter one would produce the exit code into \baz.  Should this be
  done with catcode 12 characters, or should it be done like \read, with
  the current catcodes?

2.3. \skylineskiplimit, \skylinehorizontallimit
  see section 1.1.1

2.4. \directioncode (May 1993)
 A \directioncode (with syntax analogous to \uccode, \lccode, sfcode) to be
 assigned to each input character. The basic ones are
  0 -- transparent (space, full stop...)
  1 -- left-to-right (latin letters, digits...)
  2 -- right-to-left (hebrew letters, arab letters...),
 a truly international NTS will also have codes for vertical typesetting
 and some special cases.

 The question is how to use this idea consistently. One could extend the
 notion of TeX's modes. Horizontal mode is in fact left-to-right mode, a
 right-to-left mode is missing. To be complete, this mode will be equipped
 with boxen and all the stuff TeX's left-to-right (aka horizontal) mode has.

 At the beginning of a paragraph NTS decides which mode to choose by the
 \directioncode of the first input character. Sometimes the first character
 will have the wrong code, in this case the insertion of an explicit
 control sequence (like \lrbox{}) is necessary. If a character with another
 directioncode occurs, NTS starts a \rlbox and finishes it as soon as a
 character with the original \directioncode appears or at the end of the
 paragraph.

  For the building of right-to-left tables a \rlalign is needed.

2.5. \textcode (Sep 93, Nov 93)
 Some of the character coding discussions in the Technical Working
 Group on Multiple Language Coordination and some experiences I've made
 with `german.sty' (specially the problems with an active doublequote
 and hex integer constants!) lead to this _incomplete_ proposal/idea
 for the following addition:
   Introduce something like
        \textcode       (and \textchar & \textchardef)
 which are the text (hmode) equivalent of TeX's \mathcode (and
 \mathchar/\mathchardef) primitives.

 With an equivalent and appropriate implemented \textcode primitive
 (with the choice to define a character as "pseudo-active"), it would
 be possible to
        * relate characters to different fonts
          (using a generalized `fam' of \mathcode)

        * suppress expansion of active characters (it will only be
          expanded, if it is read to form the hlist)
          (using an equivalent \mathcode="8000 value)
          [This point allows the use of e.g. a pseudo-active "
          which expands to non-expandable tokens and it removes
          the special construct \relax\ifmmode... for active
          characters, too.]

2.6. \afterfi (August 1993)
 In the answer to an exercise of the ``Around the Bend'' series, Michael Downes
 realised the non-existence of an \afterfi primitive (Note: He did not
 demand it nor really miss it). Perhaps an \afterfi can
 simplify some obscure mouth-only macros with nested conditionals???
 \afterfi should be expandable, because \if...\fi is expandable.

2.7. \interactionmode   (Nov 93, was: \currentinteractionmode)
  Add a new count register \interactionmode, which reflects the user
  interaction level with the following values:
        <= 0    batch_mode
         = 1    nonstop_mode
         = 2    scroll_mode
        >= 3    error_stop_mode

  The commands \batchmode...\errorstopmode, the "options" 'Q', 'R', 'S'
  in the interactive error routine and all other TeX internal
  interaction level changes (e.g. after an interruption) access this new
  register.  The level changes in the interactive error routine and the
  old commands should always work, even if the symbol \interactionmode is
  redefined (this means that the user can redefine \interactionmode, but the
  commands \batchmode...\errorstopmode still work).

  Examples:

   \ifnum\interactionmode<1 \AskUser \else \UseDefault \fi

  {\interactionmode=0            % switch to \batchmode
   \global\font\test=xyz10   % try to load font
  }%                         % restore former interaction level
  % ... now test if font has been loaded
  %      without error (i.e. != nullfont)

  Status:

  Bernd Raichle has made and implemented the necessary changes in his local
  TeX version.  They have to be tested and checked for forgotten things.

2.8. \mathspacing (Nov 93)
  Add a new count register array \mathspacing with 64 entries (we really
  need only 64-8=56 entries, because some of them are never used, but to
  simplify things 64 are used) with the following syntax:

   \mathspacing <num1>=<num2>           %  0 <= <num1> <= 63

  The spacing specified in number <num2> is inserted between the two
  math atom types specified in number <num1>.  The two numbers are coded
  as

  <num1> = <left_atom_type> * 8 + <right_atom_type>
  <num2> = ( (<display_spacing> * 256 + <text_spacing>) * 256
                 + <script_spacing> ) * 256 + <scriptscript_spacing>

  This means that <num1> is easily expressed in octal and <num2> in
  hexadecimal notation.

  <..._atom_type> is one of the following seven types:

  0 ordinary            1 large operator
  2 binary operation    3 relation
  4 opening             5 closing
  6 punctuation         7 delimited subformula

  <..._spacing> can be specified separately for each of the four math
  styles (display, text, script and scriptscript) with the following
  values:

        0       no space
        1       thin space      (specified by \thinmuskip)
        2       medium space    ( -- " -- \medmuskip)
        3       thick space     ( -- " -- \thickmuskip)

        4-255   reserved for other things
                (e.g. other spacings and/or additional penalties,
                like \relpenalty, \binoppenalty, ...)

  For more information see TeXbook, pp. 170f & Appendix G and TeX--The
  Program, \S 764ff.

  Examples:  (using TeX's standard spacing)

  Between an `ordinary' (= 0) and a `relation' (= 3) atom a thick
  space (= 3) is inserted, but not in script or scriptscript style.

        \mathspacing '03 = "0033

  Between a large operator (= 1) and an ordinary (= 0) atom a thin
  space (= 1) is inserted:

        \mathspacing '10 = "1111

  Status:

  Necessary changes for the sketched proposal are very simple to
  implement.
  The syntax of \mathspacing is awful, but this is true for \mathcode,
  \delimitercode, etc.etc., too.

2.9. \inputescapechar (Nov 93, alternative names were proposed during
  discussion)
  Use two new internal count registers \inputescapechar and
  \outputescapechar to specify the "escape" character to be used for
  unprintable characters.
  If \inputescapechar is not in [0..255], TeX's behaviour is used,
  i.e., two equal characters with category 7 are used as a prefix for a
  ^^x notated character, otherwise two characters with code
  \inputescapechar are used for this prefix.
  If \outputescapechar is not in [0..255], the character `^' is used
  when an unprintable character has to be written.

  The default values of these two registers are
    \inputescapechar  = -1
    \outputescapechar = `^
  to be compatible with TeX's standard behaviour.

  Problems:

  What's the behaviour of e-TeX when the \outputescapechar is
  unprintable for this TeX implementation (remember that it is only
  necessary that a subset of ASCII is printable; more in TeXbook, end of
  Appendix C), e.g.,
     \outputescapechar=`^^M
  Do we really want to make this possible?  How to prevent such
  situations (e.g. by restricting the values of \outputescapechar to a
  subset of ASCII, which is printable for all TeX implementations)?

  Relation between \newlinechar and \outputescapechar?
  IMO \outputescapechar (and all other characters in the ^^x notation
  for an unprintable character) should never result in a written
  newline, which is TeX's behaviour for versions >= 3.141.

  Status:

  The necessary changes are simple (for TeX version >= 3.141).  I have
  made changes for \outputescapechar in my local TeX version to allow
  the specification of all printable characters in a "TeX code page"
  definition (the \outputescapechar register changes are the only thing
  needed to complete the change).
  The problems mentioned above have to be discussed before e-TeX can
  contain this extension.

2.10. \middle (Jan 94)
  Generalize the syntax of \left<delimiter>  <formula> \right<delimiter>
  to allow one or more optional \middle delimiters,
  \left<delimiter> <formula> \middle<delimiter> <formula> \right<delimiter>.

  The middle delimiter grows to the same height as the left and right ones.
  Constructions of this kind are used throughout quantum mechanics (Dirac
  notation), e.g.
  $$
  \left\langle A  \middle: \hat{O} \middle: B \right\rangle
  $$
  By default, the \middle element is \mathrel, you can make it
  \mathord by embracing it {\middle :}.


2.11. \outputunit (Dec 93)
  \outputunit       unit to be used when e-TeX shows some dimen or glue
                    value
  Usage: \outputunit=<unit of measure>       (s. TeXbook p. 270)
  Rationale:

  Currently TeX forces the user to think in points when it outputs any
  dimen or glue value (e.g. when issueing an overfull hbox warning).
  But a program should adapt to the conventions of the user instead the
  other way round. The addition of \outputunit whould make TeX much
  more user-friendly, since only a few people are thinking in points.

3. Metaremarks

3.0. General
  Remarks about group efforts vs. one person creating software (Mar 93),
  ALGOL 68 as a warning example

3.1. TeX is not perfect (Jun 92, Jul 92)
  The discussion has taken place in June and July 1992. Several details were
  worked out, where TeX could be improved. Another point of criticism was
  the programming language of TeX in general, several participants prefer a
  procedural language over a macro language.

3.2. In which language shall NTS be written (Mar 93)
  In 1992, there was much discussion, in which language an NTS should be
  implemented (candidates were LISP, C, and WEB). This has settled in March
  1993 (to PASCAL-WEB), because of the acceptance of the
  idea that rather than wait for an ``all-singing, all dancing'' NTS, the
  group should develop, in a stepwise manner, small but significant
  enhancements to TeX. This implies that the enhancements are implemented as
  change files in WEB.

3.3. The TeX language (Oct/Nov 93)
  The TeX language is a simple language in the sense, that it contains only
  few concepts. It belongs to the Lisp family. In particular, it's a
  list-based macro language with late binding. Actually, that's all one
  needs to say to characterize it.
  Its data constructs are simpler than in Common Lisp: `token list' is the
  only first order type. Glue, boxes, numbers, etc., are engine
  concepts; instances of them are described by token lists.
  Its lexical analzsis is simpler than CL: One cannot program
  it. One can only configure it.
  Its control constructs are simpler than in CL: Only macros, no
  functions. And the macros are only simple ones, one can't compute
  in them.

3.4. The TeX engine (Oct/Nov 93)
  The TeX engine lies below the TeX language. Glue, boxes, numbers, etc.
  belong to the TeX engine. The registers of the engine can be changed
  by TeX's primitives. However, those seem to be quite unregular and
  baroque.

4. Deviations

4.0. General
  (empty)

4.1. Automated Kerning (Oct 92)
  Kindersley's "optical kerning": for the purposes of
  kerning, each character is replaced by a circle centred on the centre of
  gravity of that character; the radius of the circle is determined by the
  fourth moment of the character (that is, the fourth root of the sum over
  all black pixels of the fourth power of their distance from the centre). On
  the UKTUG trip to Kindersley's studio, I tried to extract the reason why
  the fourth, as opposed to third or fifth or whatever, moment is used; the
  reason is apparently that it "looks right".

  We can construct elaborate schemes for kerning (Kindersley's fourth
  moments, FontStudio's (convex?) envelopes, Calamus' eight widths, etc), but
  the proof of the typographical pudding is in the eating of the resulting
  words, so to speak.

4.2 About Lout (June 1993)
 In June 1993, the new system Basser Lout caused several questions and
 suggestions on this list. The following is taken from a short review
 of Lout by Bernd Raichle:

 `Lout' is a (yet another) document formatting system, released under
 the terms of the GNU General Public License and available on some ftp
 servers.

 IMHO it's more like a `troff' (with a better input language and some
 newer concepts) than a `TeX'.

 A few citations from the documentation of lout:

   Lout is a high-level language for document formatting, designed and
   implemented by the author.  The implementation, known as Basser
   Lout, is a fully operational production version written in C for the
   Unix operating system, which translates Lout source code into
   PostScript, a device-independent graphics rendering language
   accepted by many high-resolution output devices, including most
   laser printers.
 [...]
   When expert users can implement such applications quickly,
   non-experts benefit.  Although Lout itself provides only a small
   kernel of carefully chosen primitives,

 Lout has 23 primitive operators... missing, for example, the simplest
 arithmetical operators (there is only the operator "@Next" which
 increases a number by one).

   packages written in Lout and distributed with Basser Lout provide an
   unprecedented array of advanced features in a form accessible to
   non-expert users.  The features include rotation and scaling, fonts,

 These features are mostly based on the output language... Postscript
 (if you are looking inside a Lout package, you find large portions of
 embedded Postscript code).

   paragraph and page breaking,

 TeX does a better job for these two items, because Lout is missing
 most of TeX's paragraph/page breaking parameters.  (Note: Lout uses
 TeX's hyphenation algorithm and the hyphenation patterns.)

   displays and lists, floating figures and tables, footnotes, chapters
   and sections (automatically numbered), running page headers and
   footers, odd-even page layouts, automatically generated tables of
   contents, sorted indexes and reference lists, bibliographic and
   other databases (including databases of formats for printing
   references), equations, tables, diagrams, formatting of Pascal
   programs, and automatically maintained cross references.

 TeX's math setting abilities are better.  Lout uses a package named
 `eq' derived from the `eqn' preprocessor used with `troff'.  And there
 are other packages named `tab' (for tabulars) and `fig' (drawing
 figures).

 [...]
   Lout is organized around four key concepts -- objects, definitions,
   galleys, and cross references -- [...]

 The concept of `galleys' and the "expansion" of recursive defintions
 are IMHO the only new concept in Lout:

 `galleys' are a way to describe a page, dividing it in certain regions
 which can be filled from different sources (e.g. a footnote galley is
 filled with footnote text, etc.).

 Recursive definitions are very simple, e.g.
        def @Leaders { ..   @Leaders }
 defines the command (Lout calls it `object') to "expand" to a `..' and
 if there is place for another "expansion" it is called again.

 For example
        \hbox to 4in{Chapter 7 \dotfill 53}
 is in Lout
        4i @Wide { Chapter 7  @Leaders  53 }

 With this recursive definitions, a whole document is defined as a
 @PageList consisting of a @Page and a @PageList with an incremented
 @PageNum.  A @Page is defined as a set of `galleys' (header, text
 body, footnotes, footer), which are also defined as a list of
 text/footnotes/... and so on.

 Perhaps others can add more impressions, mine are based on the
 documentation coming with the Lout package and some tests done in
 1-2 hours.

5. Proposed changes to METAFONT

5.O. General
  Most of the General points in the discussion of TeX also apply to METAFONT.

5.1. Writing to auxiliary files
  METAFONT should be able to write to auxiliary files. Desparately needed
  for packages which allow to draw figures in METAFONT and label them in TeX
  (BoF session at EuroTeX '92, Prague).


6. Proposed changes to the tfm file format

6.1. Vertical kerning (Jun 92)
   This may sound exotic to you, but the AFM format can do
   it. And I desperately need it for non-Latin alphabets (everytime I need
   a character in a ligature raised or lowered, I have to reserve a position
   in the font for it).

6.2. Cross-font ligatures (Jun 92)
   Ligatures pointing to other fonts!! Yes, imagine for example that your
   256 chars are full, you could still access characters by ligatures...but
   they have to be in the same font.

7. Proposed changes to the dvi file format

7.0. General
  A longer discussion about colour inclusion into the dvi-file occured in
  Oct/Nov 93. The outcome was, that high-quality colour handling is a difficult
  and device dependent task, better left to the printer driver. Colour can be
  handled by the \special command which is sent directly to the driver.

8. Additions to the TeX kit

8.0. General
  The TeX kit, meaning the bundle of programmes building up a complete TeX
  installation, contains besides the major programmes TeX and METAFONT
  additional programmes, traditionally divided into several groups:

  a) TeXware: dvitype, tftopl, pltotf, pooltype, pktype, patgen, vftovp,
     vptovf, (outdated: pxtopk, pktopx)
  b) MFware: mft, gftodvi, gftopk, (outdated: gftopxl)
  c) webware: weave, tangle

  And, of course, drivers for the screens and printers.

  Other utility programmes more loosely associated with TeX are indexers
  (makeindex, idxtex, glotex, ...) and bibliography tools (bibtex,
  bibclean, ...). Makeindex and Bibtex are standard tools, because they
  are described in the LaTeX manuals.

8.1. dvicopy
  Written in WEB by Peter Breitenlohner
  Available from CTAN
  Resolves all references to virtual fonts in a dvi file. Can be used to
  create a dvi file without virtual fonts (e.g. for drivers which cannot
  handle vf's).

8.2. dvitodpl and dpltodvi
  Written in C by Geoffrey Tobin
  Available ?
  dvitodpl makes a human readable file from a dvi file. The companion
  programme dpltodvi makes a dvi file frome a dvi property list file.
  It allows you to change dvi files with a text editor.

8.3. gftotxt
  Written in C by Yannis Haralambous
  Available ?
  Extracts a certain kind of specials from the gf file into a text file.
  Workaround for the famous non-ability of METAFONT to write auxiliary
  files.

8.4. qdtexvpl
  Written by Eberhard Mattes
  Part of the emtex distribution (CTAN)
  Generates a virtual font from TeX macros. qd = quick and dirty.

8.5. fontinst
  Written in TeX by Alan Jeffrey
  Available form CTAN
  Makes virtual fonts from afm files (PostScript fonts). Used by the LaTeX
  team to create virtual fonts and fd files for LaTeX2e.

8.6. afmtotfm
  Written in C by Thomas Rokicki
  Available from CTAN (part of dvips distribution)
  Makes tfm files from afm files.


9. Existing extensions to TeX

9.0 General
  Here I include short description of existing extensions to TeX. This section
  does not include commercial TeX implementations because of lack of solid
  enough information on them. It also does not yet include ETeX, NTS, nor
  Omega.

9.1. TeX-XeT (Don Knuth and Pierre MacKay)
  CTAN: tex-archive/systems/knuth
  Adds new primitives \beginR, \endR, \beginL, and \endL for right to left
  typesetting. Despite their names, the new primitives are insensitive to
  TeX's grouping mechanism. Outputs a special file in dvi-ivd format, which
  need be resolved by another programme or requires special drivers.

9.2. TeX--XeT (Peter Breitenlohner)
  Available from CTAN  tex-archive/systems/knuth/tex--xet
  Implements the same primitives as TeX-XeT, but outputs a normal dvi file.
  Passes the trip test (as far as I know).

9.3. MLTeX (Michael Ferguson)
  Available from  aldebaran.ee.mcgill.ca in pub/mltex
  Adds a primitive \charsubdef, which allows the following: input of 8-bit
  characters, participation of accented characters not present in the output
  encoding in hyphenation, ligatures and kerning with accented letters.
  Especially popular in francophone countries.
  emTeX supports MLTeX via the /ml option.

9.4. SiSiSi (Wilhelm Barth, Heinrich Nirschl, Heini Hofstaedter und Harald
               Mueller)
  Available from CTAN: tex-archive/systems/vms (sic!)
  Implements another hyphenation algorithm (the name means SIchere
  SInnentsprechende SIlbentrennung, which is translated `secure sensitive
  hyphenation') specific to the german language (with Haupt- und
  Nebentrennstellen). Fails the trip test, therefore not a legitimate TeX.
  In use at TU Wien (Austria).

The End.

========================================================================
Date:         Tue, 11 Oct 1994 09:25:23 +0100
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: Robin Fairbairns <Robin.Fairbairns@CL.CAM.AC.UK>
Subject:      Re: Frequently asked questions -- 4th edition
In-Reply-To:  J%org Knappen's message of "Mon,
              10 Oct 1994 18:03:48 BST."
              <"swan.cl.cam.:181900:941011054028"@cl.cam.ac.uk>

J%org gives an ftp address for the FAQ; I would propose that it ought
also to be available via CTAN.

What do others think?  An appropriate place would seem to me to be
info/NTS-FAQ, not (since it's not a current product) help/NTS-FAQ
where the TeX-FAQ is.

Robin Fairbairns

Robin (Campaign for the Third Programme) Fairbairns  rf@cl.cam.ac.uk
U of Cambridge Computer Lab, Pembroke St, Cambridge  CB2 3QG, UK
Private page: http://www.cl.cam.ac.uk/users/rf/robin.html

========================================================================
Date:         Tue, 11 Oct 1994 08:34:27 CDT
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: "George D. Greenwade" <bed_gdg@SHSU.EDU>
Subject:      Re: Frequently asked questions -- 4th edition

On Tue, 11 Oct 1994 09:25:23 +0100, Robin Fairbairns
<Robin.Fairbairns@cl.cam.ac.uk> posted:
> J%org gives an ftp address for the FAQ; I would propose that it ought also
> to be available via CTAN.
>
> What do others think?  An appropriate place would seem to me to be
> info/NTS-FAQ, not (since it's not a current product) help/NTS-FAQ where the
> TeX-FAQ is.

I honestly don't know what the NTS-FAQ document is, but my suspicion is
that it answers questions about NTS and not the CTAN.  If so, it belongs in
info/ (originally named documentation/) and not help/.  The purpose of
help/ is for documentation and assistance about the CTAN itself.  Looking
through the TWG-TAG discussions some time back, the TeX-FAQ was placed in
help/ instead of info/(documentation/) as most of the issues discussed in
it as far as software and "how/where do I get..." questions were answered
in it and the grand intent way back when was to reduce those questions to
"CTAN".

--George

========================================================================
Date:         Tue, 11 Oct 1994 19:06:58 +0100
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: "J%org Knappen, Mainz" <KNAPPEN@VKPMZD.KPH.UNI-MAINZ.DE>
Subject:      Re: Frequently asked questions -- 4th edition

Robin,

placing the faq also on CTAN is fine with me.

--J"org Knappen.

========================================================================
Date:         Thu, 13 Oct 1994 18:59:42 +1000
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: Geoffrey TOBIN <ecsgrt@LUXOR.LATROBE.EDU.AU>
Subject:      dvitodpl and dpltodvi (see FAQ)

Regarding dvitodpl and dpltodvi.  Those programs, which I have lazily
named dv2dp and dp2dv, have been quietly :-) available on request
since 1992.

I wanted to refine them, but other tasks have taken precedence.  If
people don't mind a tentative, poorly documented, pair of programs,
then I'll upload them.

REMARK:
The first version of dv2dp took an afternoon to write from scratch,
using the (now-disbanded) TUG DVI Drivers committee's DVI description.
It is a continual puzzle to me that a two-way translation for dvi
format similar to tfm <-> pl, vf <-> vpl and gf <-> chr, seems not to
have been previously distributed, even if only for completeness' sake.

The DPL format is presently fairly compact, expanding DVI files by an
average of threefold.  However, having recently read Joachim Schrod's
description of the Virtual Font commands, I'm wondering whether DPL
should be totally remodeled to resemble VPL, because VF is very
similar to DVI, and VPL is in the Knuthian Property List style.

Perhaps dv2dp and dp2dv should see the light of day, to promote
discussion?

Best wishes!
Geoffrey Tobin

========================================================================
Date:         Thu, 13 Oct 1994 10:19:42 +0100
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: Anselm Lingnau <lingnau@TM.INFORMATIK.UNI-FRANKFURT.DE>
Subject:      Re: dvitodpl and dpltodvi (see FAQ)
In-Reply-To:  (Geoffrey TOBIN <ecsgrt@LUXOR.LATROBE.EDU.AU> 's message of Thu,
              13 Oct 1994 18:59:42 +1000.)
              <9410130900.AA31283@gauss.math.uni-frankfurt.de>

Geoffrey TOBIN <ecsgrt@LUXOR.LATROBE.EDU.AU> writes:

> I'm wondering whether DPL
> should be totally remodeled to resemble VPL, because VF is very
> similar to DVI, [...]

It would be nice to be able to convert a DVI file to a virtual font, if only
to ease including complex PicTeX output into documents without causing TeX
to burst because of insufficient main memory.

Anselm
--
Anselm Lingnau ......................... lingnau@tm.informatik.uni-frankfurt.de
The reward of a thing well done is to have done it.     --- Ralph Waldo Emerson

========================================================================
Date:         Thu, 13 Oct 1994 10:45:12 +0100
Reply-To: NTS-L Distribution list <NTS-L%DHDURZ1.BITNET@vm.gmd.de>
From: drucbert <drucbert@RESEAU.ONECERT.FR>
Subject:      Re: dvitodpl and dpltodvi (see FAQ)

If you have memory oveflows when using PiCTeX, perhaps
the ``dvipaste'' program may help you. It is very handful
and rather easy to use.

Jean-Pierre Drucbert
drucbert@reseau.onecert.fr