%% This is part of the OpTeX project, see http://petr.olsak.net/optex

\_codedecl \normalbaselineskip {Parameter settings <2021-04-13>} % preloaded in format

   \_doc -----------------------------
   \secc Primitive registers
   The primitive registers with the same default value as in plain \TeX/ follow:
   \_cod -----------------------------

\_parindent=20pt     % indentation of paragraphs
\_pretolerance=100   % parameters used in paragraph breaking algorithm
\_tolerance=200
\_hbadness=1000
\_vbadness=1000
\_doublehyphendemerits=10000
\_finalhyphendemerits=5000
\_adjdemerits=10000
\_uchyph=1
\_defaulthyphenchar=`\-
\_defaultskewchar=-1
\_hfuzz=0.1pt
\_vfuzz=0.1pt
\_overfullrule=5pt
\_linepenalty=10     % penalty between lines inside the paragraph
\_hyphenpenalty=50   % when a word is bro-ken
\_exhyphenpenalty=50 % when the hyphenmark is used explicitly
\_binoppenalty=700   % between binary operators in math
\_relpenalty=500     % between relations in math
\_brokenpenalty=100  % after lines if they end by a broken word.
\_displaywidowpenalty=50   % before last line of paragraph if display math follows
\_predisplaypenalty=10000  % above display math
\_postdisplaypenalty=0     % below display math
\_delimiterfactor=901 % parameter for scaling delimiters
\_delimitershortfall=5pt
\_nulldelimiterspace=1.2pt
%\_scriptspace=0.5pt % \Umathspaceafterscript used in \_setmathdimens, \_setunimathdimens instead
\_maxdepth=4pt
\_splitmaxdepth=\_maxdimen
\_boxmaxdepth=\_maxdimen
\_parskip=0pt plus 1pt
\_abovedisplayskip=12pt plus 3pt minus 9pt
\_abovedisplayshortskip=0pt plus 3pt
\_belowdisplayskip=12pt plus 3pt minus 9pt
\_belowdisplayshortskip=7pt plus 3pt minus 4pt
\_parfillskip=0pt plus 1fil
\_thinmuskip=3mu
\_medmuskip=4mu plus 2mu minus 4mu
\_thickmuskip=5mu plus 5mu

   \_doc -----------------------------
   Note that `\topskip` and `\splittopskip` are changed when first
   `\typosize` sets the main values (default font size and default
   `\baselineskip`).
   \_cod -----------------------------

\_topskip=10pt       % top edge of page-box to first baseline distance
\_splittopskip=10pt

   \_doc -----------------------------
   \secc Plain \TeX/ registers
   Allocate registers that are used just like in plain \TeX/.\nl
   \`\smallskipamount`, \`\medskipamount`, \`\bigskipamount`,
   \`\normalbaselineskip`, \`\normallineskip`,\nl \`\normallineskiplimit`,
   \`\jot`, \`\interdisplaylinepenalty`, \`\interfootnotelinepenalty`.
   \_cod -----------------------------

% We also define special registers that function like parameters:
\_newskip\_smallskipamount \_smallskipamount=3pt plus 1pt minus 1pt
\_newskip\_medskipamount \_medskipamount=6pt plus 2pt minus 2pt
\_newskip\_bigskipamount \_bigskipamount=12pt plus 4pt minus 4pt
\_newskip\_normalbaselineskip \_normalbaselineskip=12pt
\_newskip\_normallineskip \_normallineskip=1pt
\_newdimen\_normallineskiplimit \_normallineskiplimit=0pt
\_newdimen\_jot \_jot=3pt
\_newcount\_interdisplaylinepenalty \_interdisplaylinepenalty=100
\_newcount\_interfootnotelinepenalty \_interfootnotelinepenalty=100

\_public \smallskipamount \medskipamount \bigskipamount
   \normalbaselineskip \normallineskip \normallineskiplimit
   \jot \interdisplaylinepenalty \interfootnotelinepenalty ;

   \_doc -----------------------------
   Plain \TeX/ macros for setting parameters.
   \`\normalbaselines`, \`\frenchspacing`, \`\nonfrenchspacing`.
   \_cod -----------------------------

\_def\_normalbaselines{\_lineskip=\_normallineskip
  \_baselineskip=\_normalbaselineskip \_lineskiplimit=\_normallineskiplimit}

\_def\_frenchspacing{\_sfcode`\.=1000 \_sfcode`\?=1000 \_sfcode`\!=1000
  \_sfcode`\:=1000 \_sfcode`\;=1000 \_sfcode`\,=1000 }
\_def\_nonfrenchspacing{\_sfcode`\.=3000 \_sfcode`\?=3000 \_sfcode`\!=3000
  \_sfcode`\:=2000 \_sfcode`\;=1500 \_sfcode`\,=1250 }

\_public \normalbaselines \frenchspacing \nonfrenchspacing ;

   \_doc -----------------------------
   \secc Different settings than in plain \TeX/

   Default \"baseline setting" is for 10\,pt fonts (like in plain \TeX/).
   But `\typosize` and `\typoscale` macros re-declare it if another font size is used.

   The \^`\nonfrenchspacing` is not set by default because
   the author of \OpTeX/ is living in Europe.
   If you set `\enlang` hyphenation patterns then \^`\nonfrenchspacing`
   is set.
   \_cod -----------------------------

\_normalbaselines % baseline setting, 10 pt font size

   \_doc -----------------------------
   The following primitive registers have different values than in plain \TeX/.
   We prohibit orphans, set more information for tracing boxes, set page origin
   to the upper left corner of the paper (no at 1\,in, 1\,in coordinates)
   and set default page dimensions as A4, not letter.
   \_cod -----------------------------

\_emergencystretch=20pt % we want to use third pass of paragraph building algorithm
                        % we don't need compatibility with old documents

\_clubpenalty=10000    % after first line of paragraph
\_widowpenalty=10000   % before last line of paragraph

\_showboxbreadth=150   % for tracing boxes
\_showboxdepth=7
\_errorcontextlines=15
\_tracinglostchars=2   % missing character warnings on terminal too

\_outputmode=1   % PDF output
\_pdfvorigin=0pt % origin is exactly at upper left corner
\_pdfhorigin=0pt
\_hoffset=25mm   % margins are 2.5cm, no 1in
\_voffset=25mm
\_hsize=160mm    % 210mm (from A4 size) - 2*25mm (default margins)
\_vsize=244mm    % 297mm (from A4 size) - 2*25mm (default margins) -3mm baseline correction
\_pagewidth=210 true mm
\_pageheight=297 true mm

   \_doc -----------------------------
   If you insist on plain \TeX/ values of these parameters then you can
   call the `\plaintexsetting` macro.
   \_cod -----------------------------

\_def\_plaintexsetting{%
   \_emergencystretch=0pt
   \_clubpenalty=150
   \_widowpenalty=150
   \_pdfvorigin=1in
   \_pdfhorigin=1in
   \_hoffset=0pt
   \_voffset=0pt
   \_hsize=6.5in
   \_vsize=8.9in
   \_pagewidth=8.5 true in
   \_pageheight=11 true in
   \_nonfrenchspacing
}
\_public \plaintexsetting ;

   \_doc -----------------------------
   \secc[oparams] \OpTeX/ parameters

   The main principle of how to configure \OpTeX/ is not to use only parameters.
   A designer can copy macros from \OpTeX/ and re-define them as required.
   This is a reason why we don't implement dozens of parameters,
   but we keep \OpTeX/ macros relatively simple. Example: do you want
   another design of section titles? Copy macros `\_printsec` and
   `\_printsecc` from `sections.opm` file to your macro file and re-define them.

   Notice for OPmac users: there is an important difference: all "string-like"
   parameters are token lists in \OpTeX/ (OPmac uses macros for them). The reason of
   this difference: if a user sets parameter by unprefixed (public) control sequence,
   an \OpTeX/ macro can read {\em the same data} using a prefixed (private) control sequence.

   The \`\picdir` tokens list can include a directory where image files
   (loaded by `\inspic`) are saved. Empty `\picdir` (default value) means
   that image files are in the current directory (or somewhere in the \TeX/
   system where \LuaTeX/ can find them). If you set a non-empty value to
   the `\picdir`, then it must end by `/` character, for example
   `\picdir={img/}` means that there exists a directory `img` in your
   current directory and the image files are stored here.
   \_cod -----------------------------

\_newtoks\_picdir
\_public \picdir ;

   \_doc -----------------------------
   You can control the dimensions of included images by
   the parameters \`\picwidth` (which is equivalent to \`\picw`) and
   \`\picheight`. By default these parameters are set to zero: the native
   dimension of the image is used. If only `\picwidth` has a nonzero value,
   then this is the width of the image (height is calculated automatically in
   order to respect the aspect of the image). If only `\picheight` has
   a nonzero value then the height is given, the width is calculated. If both
   parameters are non-zero, the height and width are given and the aspect
   ratio of the image is (probably) broken. We recommend setting these
   parameters locally in the group where \^`\inspic` is used in order to not
   influence the dimensions of other images. But there exist many
   situations you need to put the same dimensions to more images,
   so you can set this parameter only once before more \^`\inspic` macros.\nl
   More parameters accepted by `\pdfximage` primitive can be set in the
   \`\picparams` tokens list. For example `\picparams={page3}`
   selects page 3 from included PDF file.
   \_cod -----------------------------

\_newdimen\_picwidth   \_picwidth=0pt   \_let\picw=\_picwidth
\_newdimen\_picheight  \_picheight=0pt
\_newtoks\_picparams
\_public \picwidth \picheight \picparams ;

   \_doc -----------------------------
   \`\kvdict` is dictionary name when \~`\readkv`, \~`\kvx`, \~`\kv`, and \~`\iskv` are
   processed. The default is empty.
   \_cod -----------------------------

\_newtoks \_kvdict
\_public \kvdict ;

   \_doc -----------------------------
   The \`\everytt` is the token list used in
   \^`\begtt`...\^`\endtt` environment and
   in the verbatim group opened by \^`\verbinput` macro. You can include a
   code which is processed inside the group after basic settings were done
   On the other hand, it is processed before the scanner of verbatim text is started.
   Your macros should influence scanner (catcode settings) or printing
   process of the verbatim code or both.

   The code from the line immediately after \^`\begtt` is processed after
   the \^`\everytt`. This code should overwrite \^`\everytt` settings. Use
   \^`\everytt` for all verbatim environments in your document and use a code
   after \^`\begtt` locally only for this environment.

   The \`\everyintt` token list does similar work
   but acts in the in-line verbatim
   text processed by a pair of \^`\verbchar` characters or by \^`\code``{<text>}`.
   You can set `\everyintt={\Red}` for example if you want in-line verbatim
   in red color.
   \_cod -----------------------------

\_newtoks\_everytt
\_newtoks\_everyintt
\_public \everytt \everyintt ;

   \_doc -----------------------------
   The \`\ttline` is used
   in \^`\begtt`...\^`\endtt` environment or in the code
   printed by \^`\verbinput`. If `\ttline` is positive or zero, then the
   verbatim code has numbered lines from `\ttline+1`. The `\ttline`
   register is re-set to a new value after a code piece is printed, so next
   code pieces have numbered lines continuously. If `\ttline=-1`, then
   \^`\begtt`...\^`\endtt` lines are without numbers and \^`\verbinput` lines
   show the line numbers of inputted file. If `\ttline`\code{<-1}
   then no line numbers are printed.
   \_cod -----------------------------

\_newcount\_ttline    \_ttline=-1  % last line number in \begtt...\endtt
\_public \ttline ;

   \_doc -----------------------------
   The \`\ttindent` gives default indentation
   of verbatim lines printed by \^`\begtt`...\^`\endtt` pair or by
   \^`\verbinput`.
   \nl
   The \`\ttshift` gives the amount of shift of all verbatim lines to the right.
   Despite the \^`\ttindent`, it does not shift the line numbers, only
   the text.
   \nl
   The \`\iindent` gives default indentations used in the table of contents,
   captions, lists, bib references,
   \nl
   It is strongly recommended to re-set this value if you set `\parindent`
   to another value than plain \TeX/ default 20pt. A well-typeset
   document should have the same dimension for all indentations, so
   you should say `\ttindent=\parindent` and `\iindent=\parindent`.
   \_cod -----------------------------

\_newdimen\_ttindent \_ttindent=\_parindent % indentation in verbatim
\_newdimen\_ttshift
\_newdimen\_iindent  \_iindent=\_parindent
\_public \ttindent \ttshift \iindent ;

   \_doc -----------------------------
   The tabulator `^^I` has its category code like space: it behaves as a
   space in normal text. This is a common plain \TeX/ setting.
   But in the multiline verbatim environment it
   is active and expands to the `\hskip<dimen>` where `<dimen>`
   is the width of \`\tabspaces` spaces.
   Default `\tabspaces=3` means
   that tabulator behaves like three spaces in multiline verbatim.
   \_cod -----------------------------

\_newcount \_tabspaces   \_tabspaces=3
\_public \tabspaces ;

   \_doc -----------------------------
   \`\hicolors` can include a list of \~`\hicolor` commands with
   re-declarations of default colors
   mentioned in the `\_hicolors<name>` from `hisyntax-<name>.opm` file.
   The user can give his/her preferences about colors for
   syntax highlighting by this tokens list.
   \_cod -----------------------------

\_newtoks\_hicolors
\_public \hicolors ;

   \_doc -----------------------------
   The default item mark used between \^`\begitems` and \^`\enditems` is the bullet.
   The \`\defaultitem` tokens list declares this default item mark.
   \nl
   The \`\everyitem` tokens list is applied in vertical mode
   at the start of each item.
   \nl
   The \`\everylist` tokens list is applied after the group is opened by \^`\begitems`
   \nl
   The \`\ilevel` keeps the value of the current nesting level of the items list.
   \nl
   The \`\olistskipamount` is vertical skip above and below the items list
   if `\ilevel=1`.\nl
   The \`\ilistskipamount` is vertical skip above and below the items list
   if `\ilevel>1`.\nl
   The \`\itemskipamount` is vertical skip between list items, but not above the firts
   and below the last.
   \_cod -----------------------------

\_newtoks\_defaultitem     \_defaultitem={$\_bullet$\_enspace}
\_newtoks\_everyitem
\_newtoks\_everylist
\_newcount \_ilevel
\_newskip\_olistskipamount \_olistskipamount=\_medskipamount
\_newskip\_ilistskipamount \_ilistskipamount=0pt plus.5\_smallskipamount
\_newskip\_itemskipamount  \_itemskipamount=0pt

\_public \defaultitem \everyitem \everylist \ilevel
         \olistskipamount \ilistskipamount \itemskipamount ;
\_let \listskipamount = \_olistskipamount  % for backward compatibility

   \_doc -----------------------------
   The \^`\tit` macro includes `\vglue`\`\titskip` above the title of the document.
   \_cod -----------------------------

\_newskip\_titskip   \_titskip=40pt \_relax  % \vglue above title printed by \tit
\_public \titskip ;

   \_doc ----------------------------
   The \^`\begmulti` and \^`\endmulti` pair creates more columns. The parameter
   \`\colsep` declares the space between columns. If $n$ columns are specified
   then we have $n-1$ `\colseps` and $n$ columns in total `\hsize`. This
   gives the definite result of the width of the columns.
   \_cod ----------------------------

\_newdimen\_colsep \_colsep=20pt  % space between columns
\_public \colsep ;

   \_doc -----------------------------
   Each line in the Table of contents is printed in a group.
   The \`\everytocline` tokens list is processed here before
   the internal `\_tocl:<num>` macro which starts printing the line.
   \_cod -----------------------------

\_newtoks \_everytocline
\_public \everytocline ;

   \_doc -----------------------------
   The \`\bibtexhook` tokens list is used inside the group when `\usebib` command is
   processed after style file is loaded and before printing bib-entries.
   You can re-define a behavior of the style file here or you can modify the
   more declaration for printing (fonts, baselineskip, etc.) or you can
   define specific macros used in your `.bib` file.\nl
   The \`\biboptions` is used in the `iso690` bib-style for global options,
   see section~\ref[isobib].\nl
   The \`\bibpart` saves the name of bib-list if there are more bib-lists in
   single document, see section~\ref[bib].
   \_cod -----------------------------

\_newtoks\_bibtexhook
\_newtoks\_biboptions
\_newtoks\_bibpart
\_public \bibtexhook \biboptions \bibpart ;

   \_doc -----------------------------
   \`\everycapitonf` is used before printing caption in figures and
   \`\everycapitont` is used before printing caption in tables.
   \_cod -----------------------------

\_newtoks\_everycaptiont  \_newtoks\_everycaptionf
\_public \everycaptiont \everycaptionf ;

   \_doc -----------------------------
   The \`\everyii` tokens list is used before `\noindent` for each
   Index item when printing the Index.
   \_cod -----------------------------

\_newtoks\_everyii
\_public \everyii ;

   \_doc -----------------------------
   The \`\everymnote` is used in the \^`\mnote` group before `\noindent` which
   immediately precedes marginal note text.
   \nl
   The \`\mnotesize` is the horizontal size of the marginal notes.
   \nl
   The \`\mnoteindent` is horizontal space between body-text and marginal note.
   \_cod -----------------------------

\_newtoks\_everymnote
\_newdimen\_mnotesize   \_mnotesize=20mm   % the width of the mnote paragraph
\_newdimen\_mnoteindent \_mnoteindent=10pt % distance between mnote and text
\_public \everymnote \mnotesize \mnoteindent ;

   \_doc -----------------------------
   The \^`\table` parameters follow. The \`\thistable` tokens list
   register should be used for giving an exception for only one `\table`
   which follows. It should change locally other parameters of the `\table`.
   It is reset to an empty list after the table is printed.
   \nl
   The \`\everytable` tokens list register is applied in every table.
   There is another difference between these two registers.
   The 	`\thistable` is used first, then strut and baselineskip settings are
   done, then `\everytable` is applied and then the table is printed.
   \nl
   \`\tabstrut` configures the height and depth of lines in the table.
   You can declare `\tabstrut={}`, then normal baselineskip is used in the
   table. This can be used when you don't use horizontal nor vertical
   lines in tables.
   \nl
   \`\tabiteml` is applied before each item,
   \`\tabitemr` is applied after each item of the table.
   \nl
   \`\tablinespace` is additional vertical space between horizontal rules
   and the lines of the table.
   \nl
   \`\hhkern` gives the space between horizontal lines if they are doubled and
   \`\vvkern` gives the space between such vertical lines.
   \nl
   \`\tabskipl` is `\tabskip` used before first column,
   \`\tabskipr` is `\tabskip` used after the last column.
   \nl
   \`\tsize` is virtual unit of the width of paragraph-like table items when
   `\table pxto<size>` is used.
   \_cod -----------------------------

\_newtoks\_everytable \_newtoks\_thistable
\_newtoks\_tabiteml \_newtoks\_tabitemr \_newtoks\_tabstrut
\_newdimen\_tablinespace \_newdimen\_vvkern \_newdimen\_hhkern \_newdimen\_tsize
\_newskip\_tabskipl  \_newskip\_tabskipr
\_everytable={}        % code used after settings in \vbox before table processing
\_thistable={}         % code used when \vbox starts, is is removed after using it
\_tabstrut={\_strut}
\_tabiteml={\_enspace} % left material in each column
\_tabitemr={\_enspace} % right material in each column
\_tablinespace=2pt     % additional vertical space before/after horizontal rules
\_vvkern=1pt           % space between double vertical line and used in \frame
\_hhkern=1pt           % space between double horizontal line and used in \frame
\_tabskipl=0pt\_relax  % \tabskip used before first column
\_tabskipr=0pt\_relax  % \tabskip used after the last column
\_public \everytable \thistable \tabiteml \tabitemr \tabstrut \tablinespace
         \vvkern \hhkern \tsize \tabskipl \tabskipr ;

   \_doc -----------------------------
   The \^`\eqalign` macro can be configured by \`\eqlines` and \`\eqstyle`
   tokens lists. The default values are set in order these macro behaves
   like in Plain \TeX. The \`\eqspace` is horizontal space put
   between equation systems if more columns in \^`\eqalign` are used.
   \_cod -----------------------------

\_newtoks  \_eqlines  \_eqlines={\_openup\_jot}
\_newtoks  \_eqstyle  \_eqstyle={\_strut\_displaystyle}
\_newdimen \_eqspace  \_eqspace=20pt
\_public \eqlines \eqstyle \eqspace ;

   \_doc -----------------------------
   \`\lmfil` is \"left matrix filler" (for `\matrix` columns). The default
   value does centering because the right matrix filler is directly set to `\hfil`.
   \_cod -----------------------------

\_newtoks \_lmfil   \_lmfil={\_hfil}
\_public \lmfil ;

   \_doc -----------------------------
   The output routine uses token lists  \`\headline` and \`\footline` in the
   same sense as plain \TeX/ does. If they are non-empty then `\hfil` or `\hss`
   must be here because they are used inside `\hbox to\hsize`.

   Assume that page-body text can be typeset in different sizes and
   different fonts and we don't know in what font context the output routine
   is invoked. So, it is strongly recommended to declare fixed variants of
   fonts at the beginning of your document. For example `\fontdef\rmfixed{\rm}`,
   `\fontdef\itfixed{\it}`. Then use them in headline and footline:
   \begtt
   \headline={\itfixed Text of headline, section: \firstmark \hss}
   \footline={\rmfixed \ifodd\pageno \hfill\fi \folio \hfil}
   \endtt
   \_cod -----------------------------

\_newtoks\_headline   \_headline={}
\_newtoks\_footline   \_footline={\_hss\_rmfixed \_folio \_hss}
\_public \headline \footline ;

   \_doc -----------------------------
   The distance between the `\headline` and the top of the page text
   is controlled by the \`\headlinedist` register.
   The distance between the bottom of
   page-text and `\footline` is \`\footlinedist`.
   More precisely: baseline of
   headline and baseline of the first line in page-text have distance
   `\headlinedist+\topskip`. The baseline of the last line in page-text and
   the baseline of the footline have distance `\footlinedist`.
   Default values are inspired by plain \TeX/.
   \_cod -----------------------------

\_newdimen \_headlinedist  \_headlinedist=14pt
\_newdimen \_footlinedist  \_footlinedist=24pt
\_public \headlinedist \footlinedist ;

   \_doc -----------------------------
   The \`\pgbottomskip` is inserted to the page bottom
   in the output routine. You can set less tolerance here than
   `\raggedbotom` does. By default, no tolerance is given.
   \_cod -----------------------------

\_newskip \_pgbottomskip  \_pgbottomskip=0pt \_relax
\_public \pgbottomskip ;

   \_doc -----------------------------
   The \`\nextpages` tokens list can include settings which will be used at
   next pages. It is processed at the end of output routine with
   `\globaldefs=1` prefix. The `\nextpages` is reset to empty after
   processing. Example of usage:
   \begtt
   \headline={} \nexptages={\headline={\rmfixed \firstmark \hfil}}
   \endtt
   This example sets current page with empty headline, but next pages have
   non-empty headlines.
   \_cod -----------------------------

\_newtoks \_nextpages
\_public \nextpages ;

   \_doc -----------------------------
   The \`\pgbackground` token list can include macros which generate a
   vertical list. It is used as page background. The top-left corner of such
   `\vbox` is at the top-left corner of the paper. Example creates the
   background of all pages yellow:
   \begtt
   \pgbackground={\Yellow \hrule height 0pt depth\pdfpageheight width\pdfpagewidth}
   \endtt
   \_cod -----------------------------

\_newtoks \_pgbackground   \_pgbackground={} % for page background
\_public \pgbackground  ;

   \_doc -----------------------------
   The parameters used in \^`\inoval` and \^`\incircle` macros
   can be re-set by \`\ovalparams`, \`\circleparams` tokens lists.
   The default values (documented in the user manual) are set in the macros.
   \_cod -----------------------------

\_newtoks \_ovalparams
\_newtoks \_circleparams
%\_ovalparams={\_roundness=2pt \_fcolor=\Yellow \_lcolor=\Red \_lwidth=.5bp
%              \_shadow=N \_overlapmargins=N \_hhkern=0pt \_vvkern=0pt }
%\_circleparams={\_ratio=1 \_fcolor=\Yellow \_lcolor=\Red \_lwidth=.5bp
%                \_shadow=N \_overlapmargins=N \_hhkern=3pt \_vvkern=3pt}

\_newdimen \_roundness    \_roundness=5mm % used in \clippingoval macro
\_public \ovalparams \circleparams \roundness ;

   \_doc -----------------------------
   \OpTeX/ defines \"Standard \OpTeX/ markup language"
   which lists selected commands from chapter~1 and gives their behavior when a
   converter from \OpTeX/ document to HTML or Markdown or \LaTeX/ is used.
   The structure-oriented commands are selected here, but the commands which
   declare typographical appearance (page layout, dimensions, selected font
   family) are omitted. More information for such a converter should be
   given in \`\cnvinfo``{<data>}`.
   \OpTeX/ simply ignores this but the converter can read its configuration
   from here. For example, a user can write:
   \begtt  \catcode`\<=13
   \cnvinfo {type=html, <cnv-to-html-data>}
   \cnvinfo {type=markdown, <cnv-to-markdown-data>}
   \endtt
   and the document can be processed by \OpTeX/ to create PDF, or by a
   converter to create HTML, or by another converter to create Markdown.
   \_cod -----------------------------

\_let\cnvinfo=\_ignoreit


\_endcode %----------------------------------------------------

The behavior of document processing by \OpTeX/ is
controlled by {\em parameters}. The parameters are
\begitems
* primitive registers used in build-in algorithms of \TeX/,
* registers declared and used by \OpTeX/ macros.
\enditems
Both groups of registers have their type: number, dimension, skip, token
list.

The registers are represented by their names (control sequences). If the user
re-defines this control sequence then the appropriate register exists
steadily and build-in algorithms are using it without change. But user
cannot access its value in this case. \OpTeX/ declares two control sequences
for each register: prefixed (private) and unprefixed (public). \OpTeX/ macros use only
prefixed variants of control sequences. The user should use the unprefixed variant
with the same meaning and set or read the values of registers using the
unprefixed variant. If the user re-defines the unprefixed control sequence of
a register then \OpTeX/ macros still work without change.

%There are only a few parameters declared by \OpTeX/ macros. All of them
%are listed in this section. This is the desired feature of the \OpTeX/.
%If you want to do more
%changes which cannot be controlled by parameters listed here then you
%can copy the appropriate \OpTeX/ macro to your macro file and you
%can completely re-define it. The typical examples are `\_printsomething`
%macros which declare the design of the document.

\_endinput

History:
2021-04-13 ... \bibpart added
2021-04-07 ... \biboptions added, bug from iso690 fixed
2020-04-04 ... \tabspaces added
2020-04-03 ... \hicolors added
