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-%D \module
-%D   [       file=supp-box,
-%D        version=1995.10.10,
-%D          title=\CONTEXT\ Support Macros,
-%D       subtitle=Boxes,
-%D         author=Hans Hagen,
-%D           date=\currentdate,
-%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
-%C
-%C This module is part of the \CONTEXT\ macro||package and is
-%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
-%C details.
-
-\writestatus{loading}{ConTeXt Support Macros / Boxes}
-
-\unprotect
-
-\registerctxluafile{supp-box}{autosuffix,optimize}
-
-%D And some dimensions:
-
-\newdimen\givenwidth
-\newdimen\givenheight
-\newdimen\givendepth
-
-% \fixupboxesmode\plusone % gone: is now the default
-
-%D This module implements some box manipulation macros. Some are quite simple, some
-%D are more advanced and when understood well, all can be of use.
-%D
-%D \macros
-%D   {strutdp,strutht,strutwd}
-%D
-%D The next shortcuts save memory and keying. The width is normally zero points (if
-%D not, you're in trouble). These shortcuts can be used like a dimension, opposite
-%D to the core macros \type {\strutdepth} and alike, which are values.
-
-%D These will be overloaded in spac-ver:
-
-\def\strutdp  {\dp\strutbox}
-\def\strutht  {\ht\strutbox}
-\def\strutwd  {\wd\strutbox}
-\def\struthtdp{\htdp\strutbox}
-\def\strutgap {\dimexpr\ht\strutbox-\dp\strutbox\relax}
-
-%D \macros
-%D   {voidbox,nextbox}
-%D
-%D Let's start with an easy one. The next macro hides the ugly \type {@} in \type
-%D {\voidb@x}.
-
-\ifdefined\voidbox \else \newbox\voidbox \fi
-\ifdefined\nextbox \else \newbox\nextbox \fi
-
-%D \macros
-%D   {nextdepth}
-%D
-%D Let's start with a rather simple declaration. Sometimes we need to save the \TEX\
-%D \DIMENSION\ \type{\prevdepth} and append it later on. The name \type {\nextdepth}
-%D suits this purpose well.
-
-\newdimen\nextdepth
-
-%D \macros
-%D   {smashbox, smashboxed, smashedbox}
-%D
-%D Smashing is introduced in \PLAIN\ \TEX, and stands for reducing the dimensions of
-%D a box to zero. The most resolute one is presented first.
-
-% \permanent\protected\def\smashbox#1%
-%   {\wd#1\zeropoint
-%    \ht#1\zeropoint
-%    \dp#1\zeropoint}
-%
-% \permanent\protected\def\smashboxed#1%
-%   {\wd#1\zeropoint
-%    \ht#1\zeropoint
-%    \dp#1\zeropoint
-%    \box#1\relax}
-
-%D \macros
-%D   {hsmashbox,vsmashbox}
-%D
-%D Smashing can be used for overlaying boxes. Depending on the mode, horizontal or
-%D vertical, one can use:
-
-% \permanent\protected\def\hsmashbox#1%
-%   {\wd#1\zeropoint}
-%
-% \permanent\protected\def\vsmashbox#1%
-%   {\ht#1\zeropoint
-%    \dp#1\zeropoint}
-
-%D The next implementation is less sensitive for spurious spaces.
-
-\newcount\c_boxes_register
-
-\permanent\protected\def\smashbox
-  {\afterassignment\syst_boxes_smash_boxes_register\c_boxes_register}
-
-\def\syst_boxes_smash_boxes_register
-  {\wd\c_boxes_register\zeropoint
-   \ht\c_boxes_register\zeropoint
-   \dp\c_boxes_register\zeropoint}
-
-\permanent\protected\def\hsmashbox
-  {\afterassignment\syst_boxes_hsmashed_boxes_register\c_boxes_register}
-
-\def\syst_boxes_hsmashed_boxes_register
-  {\wd\c_boxes_register\zeropoint}
-
-\permanent\protected\def\vsmashbox
-  {\afterassignment\syst_boxes_vsmashed_boxes_register\c_boxes_register}
-
-\def\syst_boxes_vsmashed_boxes_register
-  {\ht\c_boxes_register\zeropoint
-   \dp\c_boxes_register\zeropoint}
-
-\permanent\protected\def\smashedbox
-  {\afterassignment\syst_boxes_smashed_boxes_register\c_boxes_register}
-
-\protected\def\syst_boxes_smashed_boxes_register
-  {\wd\c_boxes_register\zeropoint
-   \ht\c_boxes_register\zeropoint
-   \dp\c_boxes_register\zeropoint
-   \box\c_boxes_register}
-
-\let\smashboxed\smashedbox
-
-%D \macros
-%D   {hsmash,vsmash,
-%D    hsmashed,vsmashed}
-%D
-%D While the previous macros expected a \BOX, the next act on a content. They are
-%D some subtle differences betreen the smash and smashed alternatives. The later
-%D ones reduce all dimensions to zero.
-
-\permanent\protected\def\hsmash  {\bgroup\dowithnextboxcs\syst_boxes_hsmashed_nextbox\hbox}
-\permanent\protected\def\vsmash  {\bgroup\dowithnextboxcs\syst_boxes_vsmashed_nextbox\vbox}
-\permanent\protected\def\hsmashed{\bgroup\dowithnextboxcs\syst_boxes_smashed_nextbox \hbox}
-\permanent\protected\def\vsmashed{\bgroup\dowithnextboxcs\syst_boxes_smashed_nextbox \vbox}
-
-\protected\def\syst_boxes_hsmashed_nextbox
-  {\wd\nextbox\zeropoint
-   \box\nextbox
-   \egroup}
-
-\protected\def\syst_boxes_vsmashed_nextbox
-  {\ht\nextbox\zeropoint
-   \dp\nextbox\zeropoint
-   \box\nextbox
-   \egroup}
-
-\protected\def\syst_boxes_smashed_nextbox
-  {\ht\nextbox\zeropoint
-   \dp\nextbox\zeropoint
-   \wd\nextbox\zeropoint
-   \box\nextbox
-   \egroup}
-
-%D \macros
-%D   {smashedhbox,smashedvbox}
-%D
-%D Also handy (all dimensions zeroed):
-%D
-%D \starttyping
-%D \smashedhbox to ... {...}
-%D \smashedvbox to ... {...}
-%D \stoptyping
-
-\permanent\protected\def\smashedhbox{\hpack\bgroup\dowithnextboxcs\syst_boxes_smashed_nextbox\hbox}
-\permanent\protected\def\smashedvbox{\vpack\bgroup\dowithnextboxcs\syst_boxes_smashed_nextbox\vbox}
-
-%D First we define a helper. We use a \LUATEX\ feature in order to avoid
-%D mathpalettes.
-
-\newcount\c_boxes_math_style
-
-\protected\def\syst_boxes_math_set_nextbox#1%
-  {\c_boxes_math_style\normalmathstyle
-   \setbox\nextbox\hbox{\normalstartimath\mathsurround\zeropoint\triggermathstyle\c_boxes_math_style{#1}\normalstopimath}}
-
-%D \macros
-%D   {smash}
-%D
-%D This smash alternative takes an optional arg [whdtb] as well as is potentially
-%D catcode safer. It is needed by the math module (although the \type {\leavevmode}
-%D is not added here).
-
-\permanent\protected\def\smash
-  {\begingroup
-   \futureexpandis[\syst_boxes_smash_yes\syst_boxes_smash_nop}
-
-\def\syst_boxes_smash_nop
-  {\edef\m_boxes_smash_options{hd}%
-   \futurelet\nexttoken\syst_boxes_smash_indeed}
-
-\def\syst_boxes_smash_yes[#1]%
-  {\edef\m_boxes_smash_options{#1}%
-   \futurelet\nexttoken\syst_boxes_smash_indeed}
-
-\def\syst_boxes_smash_indeed
-  {\ifmmode
-     \expandafter\syst_boxes_smash_math
-   \orelse\ifx\nexttoken\bgroup
-     \expandafter\syst_boxes_smash_hbox
-   \else
-     \expandafter\syst_boxes_smash_text
-   \fi}
-
-\def\syst_boxes_smash_math#1%
-  {\syst_boxes_math_set_nextbox{#1}%
-   \syst_boxes_smash_process}
-
-\def\syst_boxes_smash_hbox
-  {\dowithnextboxcs\syst_boxes_smash_process\hbox}
-
-\def\syst_boxes_smash_text#1%
-  {\setbox\nextbox\hbox{#1}%
-   \syst_boxes_smash_process}
-
-\def\syst_boxes_smash_process
-  {\expandafter\syst_boxes_smash_process_option\m_boxes_smash_options\relax
-   \box\nextbox
-   \endgroup}
-
-\installcorenamespace {smashoptions}
-
-\setvalue{\??smashoptions w}{\wd\nextbox\zeropoint}
-\setvalue{\??smashoptions h}{\ht\nextbox\zeropoint}
-\setvalue{\??smashoptions d}{\dp\nextbox\zeropoint}
-\setvalue{\??smashoptions t}{\ht\nextbox\zeropoint}
-\setvalue{\??smashoptions b}{\dp\nextbox\zeropoint}
-
-\def\syst_boxes_smash_process_option#1%
-  {\ifx#1\relax\else
-     \begincsname\??smashoptions#1\endcsname
-     \expandafter\syst_boxes_smash_process_option
-   \fi}
-
-\def\syst_boxes_lower_nextbox_dp
-  {\setbox\nextbox\hpack{\lower\dp\nextbox\box\nextbox}}
-
-%D \starttabulate[|l|l|]
-%D \NC w   \NC \ruledhbox{\smash  [w]{This is some great smashing, isn't it?}} \NC \NR
-%D \NC h   \NC \ruledhbox{\smash  [h]{This is some great smashing, isn't it?}} \NC \NR
-%D \NC d   \NC \ruledhbox{\smash  [d]{This is some great smashing, isn't it?}} \NC \NR
-%D \NC tb  \NC \ruledhbox{\smash [tb]{This is some great smashing, isn't it?}} \NC \NR
-%D \NC whd \NC \ruledhbox{\smash[whd]{This is some great smashing, isn't it?}} \NC \NR
-%D \stoptabulate
-
-%D \macros
-%D   {phantom, hphantom, vphantom, mathstrut}
-%D
-%D The next implementation of \type {\phantom} cum suis does not grab an argument in
-%D the non||math case, which is better.
-%D
-%D Due to a complicated call to \type {\mathpallete} and thereby \type
-%D {\mathchoice}, the next macro looks ugly. We also take care of non||braced
-%D arguments.
-
-\permanent\protected\def\phantom {\begingroup\futurelet\nexttoken\syst_boxes_phantom_indeed  }
-\permanent\protected\def\vphantom{\begingroup\futurelet\nexttoken\syst_boxes_phantom_indeed_v}
-\permanent\protected\def\hphantom{\begingroup\futurelet\nexttoken\syst_boxes_phantom_indeed_h}
-
-\def\syst_boxes_phantom_math  #1{\syst_boxes_math_set_nextbox{#1}\syst_boxes_phantom_make  }
-\def\syst_boxes_phantom_math_v#1{\syst_boxes_math_set_nextbox{#1}\syst_boxes_phantom_make_v}
-\def\syst_boxes_phantom_math_h#1{\syst_boxes_math_set_nextbox{#1}\syst_boxes_phantom_make_h}
-
-\def\syst_boxes_phantom_hbox  {\dowithnextboxcs\syst_boxes_phantom_make  \hbox} % always hbox
-\def\syst_boxes_phantom_hbox_v{\dowithnextboxcs\syst_boxes_phantom_make_v\hbox} % always hbox
-\def\syst_boxes_phantom_hbox_h{\dowithnextboxcs\syst_boxes_phantom_make_h\hbox} % always hbox
-
-\def\syst_boxes_phantom_text  #1{\setbox\nextbox\hbox{#1}\syst_boxes_phantom_make  } % always hbox
-\def\syst_boxes_phantom_text_v#1{\setbox\nextbox\hbox{#1}\syst_boxes_phantom_make_v} % always hbox
-\def\syst_boxes_phantom_text_h#1{\setbox\nextbox\hbox{#1}\syst_boxes_phantom_make_h} % always hbox
-
-\def\syst_boxes_phantom_indeed
-  {\ifmmode
-     \expandafter\syst_boxes_phantom_math
-   \orelse\ifx\nexttoken\bgroup
-     \expandafter\syst_boxes_phantom_hbox
-   \else
-     \expandafter\syst_boxes_phantom_text
-   \fi}
-
-\def\syst_boxes_phantom_indeed_v
-  {\ifmmode
-     \expandafter\syst_boxes_phantom_math_v
-   \orelse\ifx\nexttoken\bgroup
-     \expandafter\syst_boxes_phantom_hbox_v
-   \else
-     \expandafter\syst_boxes_phantom_text_v
-   \fi}
-
-\def\syst_boxes_phantom_indeed_h
-  {\ifmmode
-     \expandafter\syst_boxes_phantom_math_h
-   \orelse\ifx\nexttoken\bgroup
-     \expandafter\syst_boxes_phantom_hbox_h
-   \else
-     \expandafter\syst_boxes_phantom_text_h
-   \fi}
-
-\def\syst_boxes_phantom_make
-  {\setbox\scratchbox\emptyhbox
-   \ht\scratchbox\ht\nextbox
-   \dp\scratchbox\dp\nextbox
-   \wd\scratchbox\wd\nextbox
-   \box\scratchbox
-   \endgroup}
-
-\def\syst_boxes_phantom_make_v
-  {\setbox\scratchbox\emptyhbox
-   \ht\scratchbox\ht\nextbox
-   \dp\scratchbox\dp\nextbox
-   \box\scratchbox
-   \endgroup}
-
-\def\syst_boxes_phantom_make_h
-  {\setbox\scratchbox\emptyhbox
-   \wd\scratchbox\wd\nextbox
-   \box\scratchbox
-   \endgroup}
-
-%D We also define plain's \type {\mathstrut}.
-
-\permanent\protected\def\mathstrut{\vphantom(} % can be made faster by inlining
-
-%D \macros
-%D   {getboxheight}
-%D
-%D Although often needed, \TEX\ does not support arithmics like:
-%D
-%D \starttyping
-%D \dimen0 = \ht0 + \dp0
-%D \stoptyping
-%D
-%D so we implemented:
-%D
-%D \starttyping
-%D \getboxheight ... \of \box...
-%D \stoptyping
-%D
-%D For instance,
-%D
-%D \starttyping
-%D \getboxheight \dimen0 \of \box0
-%D \getboxheight \someheight \of \box \tempbox
-%D \stoptyping
-%D
-%D The implementation is rather stupid:
-%D
-%D \starttyping
-%D \def\getboxheight#1\of#2\box#3%
-%D   {#1\ht#3\advance#1\dp#3\relax}
-%D \stoptyping
-%D
-%D The next alternative is slightly more clever, since it accepts \type {{12}} as
-%D well as \type {12} as box number.
-
-\permanent\protected\def\getboxheight#1\of#2\box#3%
-  {\def\next{#1\htdp\c_boxes_register}%
-   \afterassignment\next\c_boxes_register=#3}
-
-%D For a long time the following three macros were part of the grid snapping core
-%D module, but it makes more sense to have them here so that users can see them.
-%D
-%D \macros
-%D   {getnoflines, getroundednoflines, getrawnoflines}
-%D
-%D Het commando \type {\getnoflines} converteert een hoogte (dimensie) in een aantal
-%D regels en kent dit toe aan \type {\noflines}.
-%D
-%D \starttyping
-%D \getnoflines{dimensie}
-%D \stoptyping
-%D
-%D Er wordt gedeeld door \type {\openlineheight} en een hoogte van~0pt komt overeen
-%D met 0~regels. The raw alternative does not round.
-%D
-%D For a long time we had:
-%D
-%D \starttyping
-%D \newcount\noflines
-%D \newdimen\noflinesheight
-%D
-%D \def\dogetnoflines#1#2%
-%D   {\noflinesheight#2\relax
-%D    \ifzeropt\noflinesheight
-%D      \noflines\zerocount
-%D    \else
-%D      \divide\noflinesheight \openlineheight
-%D      \noflines\noflinesheight
-%D      #1\ifdim\noflines\openlineheight=#2\relax \else
-%D        \advance\noflines\ifdim#2>\zeropoint\plusone\else\minusone\fi
-%D      \fi\fi
-%D    \fi}
-%D
-%D \def\getnoflines   {\dogetnoflines\iftrue } % compensated
-%D \def\getrawnoflines{\dogetnoflines\iffalse} % no compensation
-%D \stoptyping
-%D
-%D A more recent variant is:
-
-\ifx\roundingeps\undefined \newdimen\roundingeps \roundingeps=10sp \fi
-
-\newcount\noflines
-\newdimen\noflinesheight
-
-\permanent\protected\def\getnoflines#1%
-  {\noflinesheight#1\relax
-   \ifzeropt\noflinesheight
-     \noflines\zerocount
-   \orelse\ifdim\noflinesheight>\zeropoint
-     \advance\noflinesheight-\roundingeps
-     \divide\noflinesheight\openlineheight
-     \noflines\noflinesheight
-     \advance\noflines\plusone
-   \else
-     \advance\noflinesheight\roundingeps
-     \divide\noflinesheight\openlineheight
-     \noflines\noflinesheight
-     \advance\noflines\minusone
-   \fi}
-
-\permanent\protected\def\getroundednoflines#1%
-  {\noflinesheight#1\relax
-   \ifzeropt\noflinesheight
-     \noflines\zerocount
-   \orelse\ifdim\noflinesheight>\zeropoint
-     \advance\noflinesheight\roundingeps
-     \divide\noflinesheight\openlineheight
-     \noflines\noflinesheight
-   \else
-     \advance\noflinesheight-\roundingeps
-     \divide\noflinesheight\openlineheight
-     \noflines\noflinesheight
-   \fi}
-
-\permanent\protected\def\getrawnoflines#1%
-  {\noflinesheight#1\relax
-   \ifzeropt\noflinesheight
-     \noflines\zerocount
-   \orelse\ifdim\noflinesheight>\zeropoint
-     \advance\noflinesheight\roundingeps
-     \advance\noflinesheight.5\openlineheight
-     \divide\noflinesheight\openlineheight
-     \noflines\noflinesheight
-   \else
-     \advance\noflinesheight-\roundingeps
-     \advance\noflinesheight-.5\openlineheight
-     \divide\noflinesheight\openlineheight
-     \noflines\noflinesheight
-   \fi}
-
-%D Let's proof that it works:
-%D
-%D \startbuffer
-%D \scratchdimen\dimexpr(3pt)               \getnoflines\scratchdimen  1=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight)     \getnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10.1\lineheight)   \getnoflines\scratchdimen 11=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10.5\lineheight)   \getnoflines\scratchdimen 11=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10.9\lineheight)   \getnoflines\scratchdimen 11=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight+3pt) \getnoflines\scratchdimen 11=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight+3sp) \getnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight-3sp) \getnoflines\scratchdimen 10=\the\noflines \endgraf
-%D
-%D \scratchdimen\dimexpr(3pt)               \getrawnoflines\scratchdimen  0=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight)     \getrawnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10.1\lineheight)   \getrawnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10.5\lineheight)   \getrawnoflines\scratchdimen 11=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10.9\lineheight)   \getrawnoflines\scratchdimen 11=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight+3pt) \getrawnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight+3sp) \getrawnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \scratchdimen\dimexpr(10\lineheight-3sp) \getrawnoflines\scratchdimen 10=\the\noflines \endgraf
-%D \stopbuffer
-%D
-%D \typebuffer \getbuffer
-
-%D \macros
-%D   {determinenoflines}
-%D
-%D The next macro determines the number of lines and returns it it \type
-%D {\noflines}. The macro works reasonable well as long as the content can be
-%D unboxed.
-%D
-%D \starttyping
-%D \determinenoflines{test\\test}
-%D \determinenoflines{\bfd test\\test}
-%D \determinenoflines{\definedfont[Sans at 40pt]test\\test}
-%D \stoptyping
-
-% \def\syst_boxes_determine_noflines % can be mkiv'd
-%   {\beginofshapebox
-%      \unvbox\nextbox
-%    \endofshapebox
-%    \globalscratchcounter\zerocount
-%    \reshapebox{\global\advance\globalscratchcounter\plusone}%
-%    \expandafter\egroup\expandafter\noflines\the\globalscratchcounter\relax}
-
-\def\syst_boxes_determine_noflines
-  {\expandafter\egroup\expandafter\noflines\noflinesinbox\nextbox\relax}
-
-\permanent\protected\def\determinenoflines
-  {\bgroup
-   \forgetall
-   \enforced\let\crlf\endgraf
-   \enforced\let\\\endgraf
-   \dowithnextboxcs\syst_boxes_determine_noflines\vbox}
-
-%D \macros
-%D   {doiftextelse, doiftext}
-%D
-%D When \type {\doifelse} cum suis hopelessly fail, for instance because we pass
-%D data, we can fall back on the next macro:
-%D
-%D \starttyping
-%D \doiftextelse {data} {then branch} {else branch}
-%D \doiftext     {data} {then branch}
-%D \stoptyping
-
-\permanent\protected\def\doifelsetext#1%
-  {\begingroup
-   \setbox\scratchbox\hbox % no \hpack because we can have fallbacks
-     {\settrialtypesetting
-      \ignorespaces#1\removeunwantedspaces}%
-   \ifzeropt\wd\scratchbox
-     \endgroup\expandafter\secondoftwoarguments
-   \else
-     \endgroup\expandafter\firstoftwoarguments
-   \fi}
-
-\permanent\protected\def\doiftext#1%
-  {\begingroup
-   \setbox\scratchbox\hbox % no \hpack because we can have fallbacks
-     {\settrialtypesetting
-      \ignorespaces#1\removeunwantedspaces}%
-   \ifzeropt\wd\scratchbox
-     \endgroup\expandafter\gobbleoneargument
-   \else
-     \endgroup\expandafter\firstofoneargument
-   \fi}
-
-% more efficient but maybe fragile:
-%
-%       \nospacing#1}%
-
-\let\doiftextelse\doifelsetext
-
-%D \macros
-%D   {dowithnextbox,nextbox}
-%D
-%D Sometimes we want a macro to grab a box and do something on the content. One
-%D could pass an argument to a box, but this can violate the specific \CATCODES\ of
-%D its content and leads to unexpected results. The next macro treats the following
-%D braced text as the content of a box and manipulates it afterwards in a predefined
-%D way.
-%D
-%D The first argument specifies what to do with the content. This content is
-%D available in \type {\nextbox}. The second argument is one of \type {\hbox}, \type
-%D {\vbox} or \type {\vtop}. The third argument must be grouped with \type {\bgroup}
-%D and \type {\egroup}, \type {{...}} or can be a \type {\box} specification.
-%D
-%D In \CONTEXT\ this macro is used for picking up a box and treating it according to
-%D earlier specifications. We use for instance something like:
-%D
-%D \starttyping
-%D \def\getfloat%
-%D   {\def\handlefloat{...\box\nextbox...}
-%D    \dowithnextboxcs\handlefloat\vbox}
-%D \stoptyping
-%D
-%D instead of:
-%D
-%D \starttyping
-%D \def\getfloat#1%
-%D   {...#1...}
-%D \stoptyping
-%D
-%D In this implementation the \type {\aftergroup} construction is needed because
-%D \type {\afterassignment} is executed inside the box.
-
-\permanent\protected\def\dowithnextbox#1%
-  {\def\syst_boxes_with_next_box{#1}%
-   \afterassignment\syst_boxes_with_next_box_indeed
-   \setbox\nextbox}
-
-\def\syst_boxes_with_next_box_indeed
-  {\aftergroup\syst_boxes_with_next_box}
-
-\permanent\protected\def\dowithnextboxcs#1%
-  {\let\syst_boxes_with_next_box#1%
-   \afterassignment\syst_boxes_with_next_box_indeed
-   \setbox\nextbox}
-
-%D So in fact we get:
-%D
-%D \starttyping
-%D \setbox\nextbox { \aftergroup\syst_boxes_with_next_box ... }
-%D \stoptyping
-%D
-%D or
-%D
-%D \starttyping
-%D \setbox\nextbox { ... } \syst_boxes_with_next_box
-%D \stoptyping
-%D
-%D A slower but more versatile implementation is:
-%D
-%D \starttyping
-%D \protected\def\dowithnextbox#1#2%
-%D   {\def\syst_boxes_with_next_box{#1}%
-%D    \ifx#2\hbox
-%D      \afterassignment\syst_boxes_with_next_box_indeed
-%D    \orelse\ifx#2\vbox
-%D      \afterassignment\syst_boxes_with_next_box_indeed
-%D    \orelse\ifx#2\vtop
-%D      \afterassignment\syst_boxes_with_next_box_indeed
-%D    \orelse\ifx#2\normalvcenter
-%D      \afterassignment\syst_boxes_with_next_box_indeed
-%D    \else
-%D      \afterassignment\syst_boxes_with_next_box
-%D    \fi
-%D    \setbox\nextbox#2}
-%D \stoptyping
-%D
-%D This alternative also accepts \type {\box0} and alike, but we don't really need
-%D this functionality now.
-
-%D \macros
-%D   {nextboxht,nextboxwd,nextboxdp,flushnextbox}
-%D
-%D The next couple of shortcuts saves us memory as well as \type {{}}'s in passing
-%D parameters.
-
-\permanent\def\nextboxht  {\ht\nextbox}
-\permanent\def\nextboxwd  {\wd\nextbox}
-\permanent\def\nextboxdp  {\dp\nextbox}
-\permanent\def\nextboxhtdp{\htdp\nextbox}
-
-\permanent\protected\def\flushnextbox{\box\nextbox}
-
-%D \macros
-%D   {dowithnextboxcontent}
-%D
-%D But, occasionally we do need to pass some local settings without wanting to use
-%D additional grouping. Therefore we provide:
-%D
-%D \starttyping
-%D \dowithnextboxcontent{inside}{after}{box content}
-%D \stoptyping
-%D
-%D {\em todo: Search source for potential usage!}
-
-% \protected\def\dowithnextboxcontent#1#2% inside, after
-%   {\def\syst_boxes_with_next_box_one{#2}%
-%    \def\syst_boxes_with_next_box_two{#1}%
-%    \afterassignment\syst_boxes_with_next_box_content_indeed
-%    \setbox\nextbox}
-%
-% \protected\def\dowithnextboxcontentcs#1#2% inside, after
-%   {\let\syst_boxes_with_next_box_one#2%
-%    \let\syst_boxes_with_next_box_two#1%
-%    \afterassignment\syst_boxes_with_next_box_content_indeed
-%    \setbox\nextbox}
-
-\permanent\unexpanded\def\dowithnextboxcontent#1#2% inside, after
-  {\afterassigned{#1\aftergrouped{#2}}%
-   \setbox\nextbox}
-
-\permanent\unexpanded\def\dowithnextboxcontentcs#1#2% inside, after
-  {\afterassigned{#1\aftergroup#2}%
-   \setbox\nextbox}
-
-\def\syst_boxes_with_next_box_content_indeed
-  {\syst_boxes_with_next_box_two\aftergroup\syst_boxes_with_next_box_one}
-
-%D \macros
-%D   {llap, rlap, tlap, blap, clap}
-%D
-%D Some well known friends, but we implement them our own way. We want the macros to
-%D work in both math and text mode.
-
-\def\syst_boxes_do_rlap{\hpack to \zeropoint{\box\nextbox\hss}\endgroup}
-\def\syst_boxes_do_llap{\hpack to \zeropoint{\hss\box\nextbox}\endgroup}
-\def\syst_boxes_do_clap{\hpack to \zeropoint{\hss\box\nextbox\hss}\endgroup}
-\def\syst_boxes_do_tlap{\vpack to \zeropoint{\vss\box\nextbox}\endgroup}
-\def\syst_boxes_do_blap{\vpack to \zeropoint{\box\nextbox\vss}\endgroup}
-
-\def\syst_boxes_rlap     {\begingroup\dowithnextboxcs\syst_boxes_do_rlap\hbox}
-\def\syst_boxes_llap     {\begingroup\dowithnextboxcs\syst_boxes_do_llap\hbox}
-\def\syst_boxes_clap     {\begingroup\dowithnextboxcs\syst_boxes_do_clap\hbox}
-\def\syst_boxes_math_clap{\mathpalette\syst_boxes_do_math_clap}
-\def\syst_boxes_math_llap{\mathpalette\syst_boxes_do_math_llap}
-\def\syst_boxes_math_rlap{\mathpalette\syst_boxes_do_math_rlap}
-
-\def\syst_boxes_do_math_clap#1#2{\syst_boxes_clap{\normalstartimath\mathsurround\zeropoint#1#2\normalstopimath}}
-\def\syst_boxes_do_math_llap#1#2{\syst_boxes_llap{\normalstartimath\mathsurround\zeropoint#1#2\normalstopimath}}
-\def\syst_boxes_do_math_rlap#1#2{\syst_boxes_rlap{\normalstartimath\mathsurround\zeropoint#1#2\normalstopimath}}
-
-\permanent\protected\def\rlap{\mathortext\syst_boxes_math_rlap\syst_boxes_rlap}
-\permanent\protected\def\llap{\mathortext\syst_boxes_math_llap\syst_boxes_llap}
-\permanent\protected\def\clap{\mathortext\syst_boxes_math_clap\syst_boxes_clap}
-\permanent\protected\def\tlap{\begingroup\dowithnextboxcs\syst_boxes_do_tlap\vbox}
-\permanent\protected\def\blap{\begingroup\dowithnextboxcs\syst_boxes_do_blap\vbox}
-
-%D \macros
-%D   {beginofshapebox,
-%D    reshapebox, doreshapebox,
-%D    flushshapebox,
-%D    innerflushshapebox,
-%D    shapebox,
-%D    ifreshapingbox}
-%D
-%D The next utility macro originates from some linenumbering mechanism. Due to
-%D \TEX's advanced way of typesetting paragraphs, it's not easy to do things on a
-%D line||by||line basis. This macro is able to reprocess a given box and can act
-%D upon its vertical boxed components, such as lines. The unwinding sequence in this
-%D macro is inspired by a \NTG\ workshop of David Salomon in June 1992.
-%D
-%D First we have to grab the piece of text we want to act upon. This is done by
-%D means of the duo macros:
-%D
-%D \starttyping
-%D \beginofshapebox
-%D a piece of text
-%D \endofshapebox
-%D \stoptyping
-%D
-%D When all texts is collected, we can call \type {\reshapebox} and do something
-%D with it's vertical components. We can make as much passes as needed. When we're
-%D done, the box can be unloaded with \type {\flushshapebox}. The only condition in
-%D this scheme is that \type {\reshapebox} must somehow unload the \BOX\ \type
-%D {\shapebox}.
-%D
-%D An important aspect is that the content is unrolled bottom||up. The next example
-%D illustrates this maybe unexpected characteristic.
-%D
-%D \startbuffer
-%D \beginofshapebox
-%D \em \input tufte
-%D \endofshapebox
-%D
-%D \newcounter\LineNumber
-%D
-%D \reshapebox
-%D   {\doglobal\increment\LineNumber
-%D    \hbox{\llap{\LineNumber\hskip2em}\box\shapebox}}
-%D
-%D \flushshapebox
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D \getbuffer
-%D
-%D As we can see, when some kind of numbering is done, we have to add a second pass.
-%D
-%D \startbuffer
-%D \newcounter\LineNumber
-%D \newcounter\NumberOfLines
-%D
-%D \reshapebox
-%D   {\doglobal\increment\NumberOfLines
-%D    \box\shapebox}
-%D
-%D \reshapebox
-%D   {\doglobal\increment\LineNumber
-%D    \hbox
-%D      {\llap{\LineNumber\ (\NumberOfLines)\hskip2em}%
-%D       \box\shapebox}%
-%D    \doglobal\decrement\NumberOfLines}
-%D
-%D \flushshapebox
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D \getbuffer
-%D
-%D This example shows that the content of the box is still available after flushing.
-%D Another feature is that only the last reshaping counts. Multiple reshaping can be
-%D done by:
-%D
-%D \startbuffer
-%D \beginofshapebox
-%D \flushshapebox
-%D \endofshapebox
-%D
-%D \reshapebox
-%D   {\doglobal\increment\LineNumber
-%D    \hbox{\llap{$\star$\hskip1em}\box\shapebox}%
-%D    \doglobal\decrement\NumberOfLines}
-%D
-%D \flushshapebox
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D \getbuffer
-%D
-%D The macros are surprisingly easy to follow and in fact introduce no new concepts.
-%D Nearly all books on \TEX\ show similar solutions for unwinding \BOXES.
-%D
-%D Some macros, like footnote ones, can be sensitive for reshaping, which can result
-%D in an endless loop. We therefore offer:
-%D
-%D \starttyping
-%D \ifreshapingbox
-%D \stoptyping
-%D
-%D Some \CONTEXT\ commands are protected this way. Anyhow, reshaping is aborted
-%D after 100 dead cycles.
-%D
-%D By the way, changing the height and depth of \BOX\ \type {\shapebox} results in
-%D bad spacing. This means that for instance linenumbers etc. should be given zero
-%D height and depth before being lapped into the margin. The previous examples
-%D ignore this side effect, but beware!
-%D
-%D This is ancient stuff and proably not used any more but we keep it around or
-%D maybe turn it into a module some day. It shows the kind of struggling that we
-%D needed before \LUATEX\ came around.
-
-\newif    \ifsomeshapeleft
-\newif    \ifreshapingbox
-\newif    \ifreshapingfailed % may save redundant runs
-
-\newbox   \shapebox
-\newcount \shapepenalty
-\newdimen \shapekern
-\newskip  \shapeskip
-
-\newbox   \newshapebox
-\newbox   \oldshapebox
-\newbox   \tmpshapebox
-
-\newcount \shapecounter
-
-\newevery \everyshapebox \relax
-
-\def\shapesignal{.12345678pt} % or 12345sp
-
-\permanent\protected\def\reshapebox#1%
-  {\doreshapebox
-     {#1}%
-     {\penalty\shapepenalty}%
-     {\kern   \shapekern   }%
-     {\vskip  \shapeskip   }}
-
-\def\doreshapebox#1#2#3#4% \shapebox, \shapepenalty, \shapekern, \shapeskip
-  {\global\reshapingfailedfalse
-   \ifzeropt\ht\oldshapebox
-     \setbox\newshapebox\emptyvbox
-   \else
-     \setbox\newshapebox\vbox % can be \vpack
-       {\unvcopy\oldshapebox
-        \setbox\newshapebox\emptybox
-        \shapecounter\zerocount
-        \doloop{\dodoreshapebox{#1}{#2}{#3}{#4}}}%
-     \setbox\newshapebox\box\tmpshapebox
-   \fi}
-
-\ifx\originalshapebox\undefined \let\originalshapebox\oldshapebox \fi
-
-% We will turn this into a \MKIV\ variant (we can use \type {\vpack} too).
-
-\permanent\protected\def\insertshapesignal
-  {\hpack to \shapesignal{\strut\hss}% plus \strut
-   \prevdepth\strutdp} % never \nointerlineskip
-
-\permanent\protected\def\restoreshapebox % compensates for the signal
-  {\global\setbox\tmpshapebox\vbox{\vskip-\lineheight\unvcopy\oldshapebox}}
-
-\permanent\def\dodoreshapebox#1#2#3#4% \shapebox, \shapepenalty, \shapekern, \shapeskip
-  {\ifnum\lastnodetype=\gluenodecode
-     \shapeskip\lastskip
-     \global\setbox\tmpshapebox\vbox{#4\unvbox\tmpshapebox}%
-     \unskip
-   \orelse\ifnum\lastnodetype=\kernnodecode
-     \shapekern\lastkern
-     \global\setbox\tmpshapebox\vbox{#3\unvbox\tmpshapebox}%
-     \unkern
-   \orelse\ifnum\lastnodetype=\penaltynodecode
-     \shapepenalty\lastpenalty
-     \global\setbox\tmpshapebox\vbox{#2\unvbox\tmpshapebox}%
-     \unpenalty
-   \orelse\ifnum\lastnodetype<\zeropoint
-     \exitloop
-   \else
-     \setbox\shapebox\lastbox
-     \ifvoid\shapebox
-     \orelse\ifdim\wd\shapebox=\shapesignal\relax
-       \exitloop
-     \else
-       \shapecounter\zerocount
-       \global\setbox\tmpshapebox\vbox{#1\unvbox\tmpshapebox}%
-     \fi
-   \fi
-   \ifnum\shapecounter>100 % can be less
-     \global\reshapingfailedtrue
-     \message{!!forced exit from shapebox \the\lastnodetype !!}%
-     \restoreshapebox
-     \exitloop
-   \else
-     \advance\shapecounter \plusone
-   \fi}
-
-\permanent\protected\def\beginofshapebox
-  {\setbox\oldshapebox\vbox
-     \bgroup
-     \reshapingboxtrue
-     \the\everyshapebox
-     \insertshapesignal}
-
-\permanent\protected\def\endofshapebox
-  {\endgraf
-   \egroup}
-
-\let\beginshapebox\beginofshapebox
-\let\endshapebox  \endofshapebox
-
-\permanent\protected\def\flushshapebox
-  {\bgroup
-   \ifzeropt\ht\newshapebox
-   \else
-     % make \prevdepth legal
-     % \par before the next \vskip gives far worse results
-     \ifdim\parskip>\zeropoint\vskip\parskip\else\par\fi
-     % and take a look
-     \ifdim\prevdepth=-\thousandpoint
-       \prevdepth\zeropoint
-     \fi
-     \ifdim\prevdepth<\zeropoint\relax
-       % something like a line or a signal or ...
-       \donetrue
-     \orelse\ifinner
-       % not watertight and not ok
-       \donefalse
-     \orelse\ifdim\pagegoal=\maxdimen
-       \donetrue
-     \else
-       % give the previous line a normal depth
-       \donetrue
-       {\forgeteverypar\verticalstrut}\nobreak
-       \kern-\struttotal % geen \vskip
-       \kern-\parskip
-     % \vskip-\strutdp
-     \fi
-     \scratchdimen\dp\newshapebox
-     \unvbox\newshapebox
-     % \prevdepth=0pt and \dp\newshapebox depend on last line
-     \kern-\scratchdimen % ??
-     % now \prevdepth=0pt
-     \ifdone
-       \kern\strutdp
-       \prevdepth\strutdp
-     \fi
-   \fi
-   \egroup}
-
-%D In real inner situations we can use:
-%D
-%D \starttyping
-%D \flushinnershapebox
-%D \stoptyping
-%D
-%D This one is used in \type{\framed}.
-
-% The kern fails on for instance:
-%
-% \omlijnd[offset=0pt,hoogte=8mm,uitlijnen={rechts,laho}]{\bfa test}
-
-\permanent\protected\def\innerflushshapebox
-  {\ifzeropt\ht\newshapebox \else
-     \unvcopy\newshapebox\relax % unvcopy ! else spacing problem
-   % \kern-\dp\newshapebox\relax
-   \fi}
-
-%D For absolute control, one can use \type {\doreshapebox} directly. This macro
-%D takes four arguments, that take care of:
-%D
-%D \startitemize[n,packed]
-%D \item \type{\shapebox}
-%D \item \type{\shapepenalty}
-%D \item \type{\shapekern}
-%D \item \type{\shapeskip}
-%D \stopitemize
-
-%D \macros
-%D   {shapedhbox}
-%D
-%D When constructing a new box, using the content of \type {\shapebox}, one can best
-%D use \type {\shapedhbox} instead of \type {\hbox}, since it manages the height and
-%D depth of the line.
-
-\permanent\protected\def\shapedhbox        % lines with non strutted dimensions have
-  {\expanded{\dowithnextbox       % interlineskip so if we want the original
-     {\ht\nextbox\the\ht\shapebox % spacing, we need to preserve the original
-      \dp\nextbox\the\dp\shapebox % height and depth which is definitely
-      \box\nextbox}}              % needed if we apply struts to the 'new'
-   \hbox}                         % box or do something that changed ist size
-
-%D \macros
-%D   {hyphenatedword,
-%D    hyphenatedpar,
-%D    hyphenatedfile,
-%D    dohyphenateword}
-%D
-%D We no longer use the pure \TEX\ variant. In due time we will report some more
-%D advanced statistics.
-%D
-%D \starttyping
-%D \showhyphens{dohyphenatedword}
-%D \stoptyping
-
-\permanent\protected\def\doshowhyphenatednextbox
-  {\clf_showhyphenatedinlist\nextbox}
-
-\permanent\protected\def\showhyphens % hpack: so no processing (we hyphenate in lua)
-  {\dowithnextboxcs\doshowhyphenatednextbox\hpack}
-
-%D The following macros are seldom used but handy for tracing.
-%D
-%D \starttyping
-%D \hyphenatedword{dohyphenatedword}
-%D \hyphenatedpar {\dorecurse{10}{dohyphenatedword }}
-%D \hyphenatedfile{tufte}
-%D \stoptyping
-
-\def\syst_boxes_hyphenatednextbox     {\clf_hyphenatedlist\nextbox false\relax\unhbox\nextbox}
-\def\syst_boxes_hyphenatednextboxcolor{\clf_hyphenatedlist\nextbox true \relax\unhbox\nextbox}
-
-\permanent\protected\def\hyphenatedword       {\dowithnextboxcs\syst_boxes_hyphenatednextbox\hbox}
-\permanent\protected\def\hyphenatedpar        {\dowithnextboxcs\syst_boxes_hyphenatednextbox\hbox}
-\permanent\protected\def\hyphenatedfile     #1{\dowithnextboxcs\syst_boxes_hyphenatednextbox\hbox{\readfile{#1}\donothing\donothing}}
-\permanent\protected\def\hyphenatedcoloredword{\dowithnextboxcs\syst_boxes_hyphenatednextboxcolor\hbox}
-
-%D \macros
-%D   {processtokens}
-%D
-%D We fully agree with (most) typographers that inter||letter spacing is only
-%D permitted in fancy titles, we provide a macro that can be used to do so. Because
-%D this is (definitely and fortunately) no feature of \TEX, we have to step through
-%D the token list ourselves.
-%D
-%D \starttyping
-%D \processtokens {before} {between} {after} {space} {tokens}
-%D \stoptyping
-%D
-%D An example of a call is:
-%D
-%D \startbuffer
-%D \processtokens {[} {+} {]} {\space} {hello world}
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D This results in:
-%D
-%D \getbuffer
-%D
-%D The list of tokens may contain spaces, while \type {\\}, \type {{}} and \type {\
-%D } are handled as space too.
-
-%D This can be done in a more modern way but for nostalgic reasons we keep it.
-
-\permanent\protected\def\processtokens#1#2#3#4#5%
-  {\begingroup
-   \def\lastcharacter{\lastcharacter}% hm, recursive ?
-   \enforced\permanent\def\space{ }%
-   \enforced\let\\\space
-   \def\before {#1}%
-   \def\between{#2}%
-   \def\after  {#3}%
-   \def\white  {#4}%
-   \let\savedbefore\before
-   \syst_boxes_processtokens#5\lastcharacter
-   \endgroup}
-
-\def\syst_boxes_processtokens% the space after = is essential
-  {\afterassignment\syst_boxes_do_processtokens\let\nextprocessedtoken= }
-
-\def\syst_boxes_redo_processedtoken
-  {\dowithnextbox
-     {\before{\copy\nextbox}% \before can use nextbox several times
-      \let\before\between
-      \syst_boxes_processtokens}
-      \hbox\bgroup}
-
-\def\syst_boxes_do_processtokens
-  {\ifx\nextprocessedtoken\lastcharacter
-     \after
-   \orelse\ifx\nextprocessedtoken\bgroup
-     \expandafter\syst_boxes_redo_processedtoken
-   \else
-     \expandafter\if\space\nextprocessedtoken
-       \after\white
-       \let\before\savedbefore
-     \else
-       \before\nextprocessedtoken
-       \let\before\between
-     \fi
-     \expandafter\syst_boxes_processtokens
-   \fi}
-
-%D \macros
-%D   {doboundtext}
-%D
-%D Sometimes there is not enough room to show the complete (line of) text. In such a
-%D situation we can strip of some characters by using \type {\doboundtext}. When the
-%D text is wider than the given width, it's split and the third argument is
-%D appended. When the text to be checked is packed in a command, we'll have to use
-%D \type {\expandafter}.
-%D
-%D \starttyping
-%D \doboundtext{a very, probably to long, text}{3cm}{...}
-%D \stoptyping
-%D
-%D When calculating the room needed, we take the width of the third argument into
-%D account, which leads to a bit more complex macro than needed at first sight.
-%D
-%D Sort of obsolete I guess:
-
-\def\syst_boxes_boundtext#1%
-  {\setbox\scratchboxone\hbox{#1}%
-   \advance\scratchdimen -\wd\scratchboxone
-   \ifdim\scratchdimen>\zeropoint\relax#1\fi}
-
-\permanent\protected\def\doboundtext#1#2#3% still used?
-  {\hbox
-     {\setbox\scratchbox\hbox{#1}%
-      \scratchdimen#2\relax
-      \ifdim\wd\scratchbox>\scratchdimen
-        \setbox\scratchbox\hbox{#3}%
-        \advance\scratchdimen -\wd\scratchbox
-        \handletokens#1\with\syst_boxes_boundtext
-      \fi
-      \box\scratchbox}}
-
-%D \macros
-%D   {limitatetext}
-%D
-%D A bit more beautiful alternative for the previous command is the next one. This
-%D command is more robust because we let \TEX\ do most of the job. The previous
-%D command works better on text that cannot be hyphenated.
-%D
-%D \starttyping
-%D \limitatetext {text}  {width} {sentinel}
-%D \limitatetext {text} {-width} {prelude}
-%D \stoptyping
-%D
-%D When no width is given, the whole text comes available. The sentinel is optional.
-%D This is about the third version.
-
-\ifdefined\fakecompoundhyphen\else \let\fakecompoundhyphen\relax      \fi
-\ifdefined\veryraggedright   \else \def\veryraggedright{\raggedright} \fi
-
-%D See \MKIV\ file for the older implementation.
-
-\permanent\protected\def\limitatetext#1#2#3%
-  {\splitatcomma{#2}\leftlimit\rightlimit
-   \limitated
-      left     \leftlimit
-  \ifempty\rightlimit\else
-      right    \rightlimit
-  \fi
-      strip    true
-      sentinel {#3}
-      text     {#1}
-   \relax}
-
-%D Undocumented bonus (see wiki):
-%D
-%D \starttyping
-%D \limitatefirstline{\input tufte\relax}{10cm}{\unknown}
-%D \stoptyping
-
-\permanent\protected\def\limitatefirstline#1#2#3%
-  {\hbox\bgroup\strut % \hpack
-   \setbox\scratchbox\hbox{\begstrut#1\endstrut}%
-   \ifdim\wd\scratchbox>#2\relax
-     \setbox\scratchbox\hbox{#3}%
-     \hsize#2\relax
-     \advance\hsize-\wd\scratchbox
-     \setbox\scratchbox\vbox{\forgetall\veryraggedright#1}%
-     \setbox\scratchbox\vsplit\scratchbox to \lineheight
-     \vbox
-       {\unvbox\scratchbox
-        \global\setbox\plusone\lastbox
-        \global\setbox\plusone\hbox{\strut\unhbox\plusone}%
-        \hbox % to #2 % \hpack
-          {\ifx\clip\undefined
-             \box\plusone
-           \orelse\ifdim\wd\plusone>\hsize
-             \lower\strutdepth\hpack{\clip[\c!width=\hsize,\c!height=\lineheight]{\hpack{\raise\strutdepth\box\plusone}}}%
-           \else
-             \box\plusone
-           \fi
-           \removeunwantedspaces#3}}% \removeunwantedspaces\hss#3}}%
-   \else
-     #1%
-   \fi
-   \egroup}
-
-%D \macros
-%D   {processisolatedwords,processisolatedchars}
-%D
-%D \startbuffer
-%D \processisolatedchars{some more words}           \ruledhbox \par
-%D \processisolatedchars{and some $x + y = z$ math} \ruledhbox \par
-%D \processisolatedchars{and a \hbox{$x + y = z$}}  \ruledhbox \par
-%D \processisolatedwords{some more words}           \ruledhbox \par
-%D \processisolatedwords{and some $x + y = z$ math} \ruledhbox \par
-%D \processisolatedwords{and a \hbox{$x + y = z$}}  \ruledhbox \par
-%D \stopbuffer
-%D
-%D \typebuffer \blank \getbuffer \blank
-
-% todo: provide variant with #1 picked up as box
-
-\permanent\protected\def\processisolatedchars#1#2%
-  {\dontleavehmode
-   \begingroup
-   \setbox\scratchbox\hbox{\settrialtypesetting#2{\savecurrentattributes{pic}}}%
-   \setbox\scratchbox\hbox{\restorecurrentattributes{pic}#1}%
-   \clf_applytobox
-     method  {char}%
-     box     \scratchbox
-     command {\csstring#2}%
-     nested  true%
-   \relax
-   \endgroup}
-
-\permanent\protected\def\processisolatedwords#1#2%
-  {\dontleavehmode
-   \begingroup
-   \setbox\scratchbox\hbox{\settrialtypesetting#2{\savecurrentattributes{pic}}}%
-   \setbox\scratchbox\hbox{\restorecurrentattributes{pic}#1}%
-   \clf_applytobox
-     method  {word}%
-     box     \scratchbox
-     command {\csstring#2}%
-     nested  true%
-   \relax
-   \endgroup}
-
-%D A variant:
-
-\permanent\protected\def\applytocharacters#1%
-  {\dontleavehmode
-   \dowithnextbox{\clf_applytobox
-     method  {char}%
-     box     \nextbox
-     command {\csstring#1}%
-     nested  true%
-   \relax}%
-   \hbox}
-
-\permanent\protected\def\applytowords#1%
-  {\dontleavehmode
-   \dowithnextbox{\clf_applytobox
-     method  {word}%
-     box     \nextbox
-     command {\csstring#1}%
-     nested  true%
-   \relax}%
-   \hbox}
-
-%D The old call:
-
-\permanent\protected\def\processwords#1%
-  {\processisolatedwords{#1}\processword}
-
-\let\processword\relax
-
-\permanent\protected\def\applytosplitstringchar#1#2%
-  {\dontleavehmode\clf_processsplit
-     data    {#2}%
-     command {\csstring#1}%
-     method  {char}%
-   \relax}
-
-\permanent\protected\def\applytosplitstringword#1#2%
-  {\dontleavehmode\clf_processsplit
-     data    {#2}%
-     command {\csstring#1}%
-     method  {word}%
-   \relax}
-
-\permanent\protected\def\applytosplitstringline#1#2%
-  {\dontleavehmode\clf_processsplit
-     data    {#2}%
-     command {\csstring#1}%
-     method  {line}%
-   \relax}
-
-\permanent\protected\def\applytosplitstringcharspaced#1#2%
-  {\dontleavehmode\clf_processsplit
-     data    {#2}%
-     command {\csstring#1}%
-     method  {char}%
-     spaced  true%
-   \relax}
-
-\permanent\protected\def\applytosplitstringwordspaced#1#2%
-  {\dontleavehmode\clf_processsplit
-     data    {#2}%
-     command {\csstring#1}%
-     method  {word}%
-     spaced  true%
-   \relax}
-
-\permanent\protected\def\applytosplitstringlinespaced#1#2%
-  {\dontleavehmode\clf_processsplit
-     data    {#2}%
-     command {\csstring#1}%
-     method  {line}%
-     spaced  true%
-   \relax}
-
-%D \macros
-%D   {sbox}
-%D
-%D This is a rather strange command. It grabs some box content and and limits the
-%D size to the height and depth of a \type {\strut}. The resulting bottom||alligned
-%D box can be used aside other ones, without disturbing the normal baseline
-%D distance.
-%D
-%D \startbuffer
-%D \ruledhbox to .5\hsize{\sbox{eerste\par tweede \par derde}}
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D Shows up as:
-%D
-%D \startexample
-%D \vskip3\baselineskip
-%D \getbuffer
-%D \stopexample
-%D
-%D Before displaying the result we added some skip, otherwise the first two lines
-%D would have ended up in the text. This macro can be useful when building
-%D complicated menus, headers and footers and|/|or margin material.
-
-\permanent\protected\def\sbox
-  {\vpack\bgroup
-   \dowithnextboxcs\syst_boxes_sbox_finish\vbox}
-
-\def\syst_boxes_sbox_finish
-  {\boxyoffset\nextbox-\strutdp
-   \dp\nextbox\strutdp
-   \ht\nextbox\strutht
-   \box\nextbox
-   \egroup}
-
-%D A variant on this:
-%D
-%D \starttyping
-%D xx \ruledhbox{\inlinedbox{\tfd test}} xx
-%D \stoptyping
-
-\permanent\protected\def\inlinedbox
-  {\bgroup
-   \dowithnextboxcs\syst_boxes_inlined_finish\hbox}
-
-\def\syst_boxes_inlined_finish
-  {\boxyoffset\nextbox-\dimexpr(\htdp\nextbox-\lineheight)/\plustwo+\strutdp\relax
-   \ht\nextbox\strutht
-   \dp\nextbox\strutdp
-   \box\nextbox
-   \egroup}
-
-%D \macros
-%D   {struttedbox}
-%D
-%D This boxing macro limits the height and depth to those of a strut.
-
-\permanent\protected\def\struttedbox
-  {\hpack\bgroup
-   \dowithnextboxcs\syst_boxes_struttedbox_finish\hbox}
-
-\def\syst_boxes_struttedbox_finish
-  {\dp\nextbox\strutdepth
-   \ht\nextbox\strutheight
-   \box\nextbox
-   \egroup}
-
-%D \macros
-%D   {topskippedbox}
-%D
-%D This macro compensates the difference between the topskip and strutheight. Watch
-%D how we preserve the depth when it equals strutdepth.
-
-\permanent\protected\def\topskippedbox
-  {\hpack\bgroup\dowithnextboxcs\syst_boxes_topskippedbox_finish\hbox}
-
-\def\syst_boxes_topskippedbox_finish
-  {\edef\m_boxes_tmp{\ifdim\strutdepth=\dp\nextbox\dp\nextbox\the\dp\nextbox\fi}%
-   \lower\topskip\hpack{\raise\strutheight\box\nextbox}%
-   \m_boxes_tmp
-   \egroup}
-
-%D \macros
-%D   {centeredbox, centerednextbox}
-%D
-%D Here is another strange one. This one offers a sort of overlay with positive or
-%D negative offsets. This command can be used in well defined areas where no offset
-%D options are available. We first used it when building a button inside the margin
-%D footer, where the button should have a horizontal offset and should be centered
-%D with respect to the surrounding box. The last of the three examples we show below
-%D says:
-%D
-%D \starttyping
-%D \vsize=3cm
-%D \hsize=3cm
-%D \ruledvbox to \vsize
-%D   {\centeredbox height .5cm width -1cm
-%D      {\vrule width \hsize height \vsize}}}
-%D \stoptyping
-%D
-%D Here the \type {\ruledvbox} just shows the surrounding box and \type {\vrule} is
-%D used to show the centered box.
-%D
-%D \def\AnExample#1#2%
-%D   {\vsize=3cm
-%D    \hsize=3cm
-%D    \ruledvbox to \vsize
-%D      {\centeredbox height #1 width #2
-%D         {\color[green]{\vrule width \hsize height \vsize}}}}
-%D
-%D \startlinecorrection
-%D \startcombination[3*1]
-%D   {\AnExample {-1cm}  {.5cm}} {}
-%D   {\AnExample {.5cm}  {-1cm}} {}
-%D   {\AnExample {-1cm} {-.5cm}} {}
-%D \stopcombination
-%D \stoplinecorrection
-%D
-%D This command takes two optional arguments: \type {width} and \type {height}.
-%D Observing readers can see that we use \TEX's own scanner for grabbing these
-%D arguments: \type {#1#} reads everyting till the next brace and passes it to both
-%D rules. The setting of the box dimensions at the end is needed for special cases.
-%D The dimensions of the surrounding box are kept intact. This commands handles
-%D positive and negative dimensions (which is why we need two boxes with rules).
-
-\permanent\protected\def\centeredbox#1#%   height +/-dimen width +/-dimen
-  {\bgroup
-   \dontcomplain
-   \forgetall
-   \scangivendimensions#1\relax
-   \advance\vsize\givenheight
-   \advance\hsize\givenwidth
-   \dowithnextboxcs\syst_boxes_centered_finish
-   \hbox}
-
-\def\syst_boxes_centered_finish
-  {\boxxoffset\nextbox.5\dimexpr
-      \hsize
-     -\wd\nextbox
-     -\givenwidth
-   \relax
-   \boxyoffset\nextbox.5\dimexpr
-      \vsize
-     -\ht\nextbox
-     +\dp\nextbox
-     -\givenheight
-   \relax
-   \wd\nextbox\dimexpr\hsize-\givenwidth \relax
-   \ht\nextbox\dimexpr\vsize-\givenheight\relax
-   \dp\nextbox\zeropoint
-   \box\nextbox
-   \egroup}
-
-%D For those who don't want to deal with \type {\hsize} and \type {\vsize}, we have:
-%D
-%D \starttyping
-%D \centerednextbox width 2bp height 2bp
-%D   {\framed[width=100bp,height=100bp]{}}
-%D \stoptyping
-%D
-%D Do you see why we call this one \type {next}?
-
-\permanent\protected\def\centerednextbox#1#%
-  {\bgroup
-   \dowithnextbox
-     {\hsize\wd\nextbox
-      \vsize\ht\nextbox
-      \centeredbox#1{\box\nextbox}%
-      \egroup}
-   \hbox}
-
-%D \macros
-%D   {centerbox}
-%D
-%D Centering on the available space is done by:
-%D
-%D \starttyping
-%D \centerbox <optional specs> {content}
-%D \stoptyping
-%D
-%D When omitted, the current \type {\hsize} and \type {\vsize} are used. Local
-%D dimensions are supported.
-
-\permanent\protected\def\centerbox#1#%   optional height +/-dimen width +/-dimen
-  {\bgroup
-   \dowithnextbox
-     {\setlocalhsize
-      \setbox\scratchbox\hpack{\vrule\s!width \zeropoint#1}%
-      \ifzeropt\wd\scratchbox\else\hsize\wd\scratchbox\fi
-      \setbox\scratchbox\vpack{\hrule\s!height\zeropoint#1}%
-      \ifzeropt\ht\scratchbox\else\vsize\ht\scratchbox\fi
-      \vpack to \vsize{\vss\hpack to \hsize{\hss\box\nextbox\hss}\vss}%
-      \egroup}%
-     \hbox}
-
-%D \macros
-%D   {setrigidcolumnhsize,rigidcolumnbalance,rigidcolumnlines}
-%D
-%D These macros are copied from the \TEX book, page~397, and extended by a macro
-%D that sets the \type {\hsize}.
-%D
-%D \starttyping
-%D \setrigidcolumnhsize {total width} {distance} {n}
-%D \rigidcolumnbalance  {box}
-%D \stoptyping
-%D
-%D Both these macros are for instance used in typesetting footnotes. The following
-%D flags influence the process.
-
-\newif\ifalignrigidcolumns
-\newif\ifstretchrigidcolumns
-\newif\iftightrigidcolumns    % if true: just a vbox, no depth/noflines/gridsnap corrrections
-
-\permanent\protected\def\setrigidcolumnhsize#1#2#3% todo: \dimexpr
-  {\xdef\savedrigidhsize{\the\hsize}%
-   \hsize#1\relax
-   \global\chardef\rigidcolumns#3\relax
-   \scratchdimen -#2\relax
-   \multiply\scratchdimen #3\relax
-   \advance\scratchdimen  #2\relax
-   \advance\hsize \scratchdimen
-   \divide\hsize #3\relax}
-
-% ==
-%
-% \def\setrigidcolumnhsize#1#2#3%
-%   {\xdef\savedrigidhsize{\the\hsize}%
-%    \global\chardef\rigidcolumns#3\relax
-%    \hsize=\dimexpr(#1-\numexpr#3-1\relax\dimexpr#2\relax)/#3\relax}
-
-\newbox\rigidcolumnbox
-
-\let\rigidcolumnlines\!!zerocount
-
-\permanent\protected\def\rigidcolumnbalance#1%
-  {\ifnum\rigidcolumns=1 % tzt ook h/d correctie
-     \ifinner\ifhmode\box\else\unvbox\fi\else\unvbox\fi#1\relax
-   \else
-     \vbox % \vpack
-       {\forgetall
-        \nopenalties
-        \dontcomplain
-        \setbox\rigidcolumnbox\vbox
-          {\line{}\goodbreak\unvbox#1\removebottomthings}%
-        \splittopskip\openstrutheight
-        \setbox\scratchbox\vsplit\rigidcolumnbox to \zeropoint
-        \ifcase\rigidcolumnlines\relax
-          % \iffalse
-          %  % maybe some day an option
-          %  \scratchskip\ht\rigidcolumnbox
-          %  \advance\scratchskip\dp\rigidcolumnbox
-          %  \getnoflines\scratchskip
-          %  \ifodd\noflines
-          %    \advance\noflines\plusone
-          %  \fi
-          %  \divide\noflines\rigidcolumns
-          %\else
-            \scratchdimen\ht\rigidcolumnbox
-            \divide\scratchdimen \rigidcolumns
-            \getnoflines\scratchdimen
-          %\fi
-        \else
-          \noflines\rigidcolumnlines % to be sure
-        \fi
-        \scratchdimen\noflines\lineheight
-        % new: we now loop so that we don't loose content
-        % since in practice we also use this macro for
-        % funny lineheights and border cases
-        \setbox0=\box\rigidcolumnbox
-        \doloop
-          {\setbox\rigidcolumnbox=\copy0
-           \setbox\scratchbox\hpack to \savedrigidhsize
-             {\dorecurse\rigidcolumns
-                {\setbox\scratchbox\vsplit\rigidcolumnbox to \scratchdimen
-                   \dp\scratchbox\openstrutdepth
-                   \setbox\scratchbox\vtop
-                     \ifalignrigidcolumns to
-                       \ifstretchrigidcolumns\vsize\else\scratchdimen\fi
-                     \fi
-                     {\unvbox\scratchbox}%
-                 \wd\scratchbox\hsize
-                 \box\scratchbox
-                 \hfill}%
-              \hfillneg}%
-          \ifvoid\rigidcolumnbox\exitloop\else\advance\scratchdimen\lineheight\fi}%
-       \iftightrigidcolumns
-         \setbox\scratchbox\hpack{\raise\dp\scratchbox\box\scratchbox}%
-       \else
-         \advance\scratchdimen -\openstrutdepth
-         \setbox\scratchbox\hpack{\raise\scratchdimen\box\scratchbox}%
-         \dp\scratchbox\openstrutdepth
-         \ht\scratchbox\scratchdimen
-       \fi
-       \box\scratchbox}%
-   \fi}
-
-%D \macros
-%D   {startvboxtohbox,stopvboxtohbox,convertvboxtohbox}
-%D
-%D Here is another of Knuth's dirty tricks, as presented on pages 398 and 399 of the
-%D \TEX book. These macros can be used like:
-%D
-%D \starttyping
-%D \vbox
-%D   \bgroup
-%D     \startvboxtohbox ... \stopvboxtohbox
-%D     \startvboxtohbox ... \stopvboxtohbox
-%D     \startvboxtohbox ... \stopvboxtohbox
-%D   \egroup
-%D
-%D \vbox
-%D   \bgroup
-%D     \convertvboxtohbox
-%D   \egroup
-%D \stoptyping
-%D
-%D These macros are used in reformatting footnotes, so they do what they're meant
-%D for.
-
-\newdimen\vboxtohboxslack
-\newdimen\hboxestohboxslack
-
-%D Create line and fake height of paragraph by messign with heights: a nice hack by
-%D DEK himself.
-
-%\protected\def\setvboxtohbox
-%  {\bgroup
-%   \ifdim\baselineskip<16pt \relax
-%     \scratchdimen\baselineskip
-%     \multiply\scratchdimen 1024
-%   \else
-%     \message{cropping \baselineskip to 16pt}%
-%     \scratchdimen\maxdimen
-%   \fi
-%   \divide\scratchdimen \hsize
-%   \multiply\scratchdimen 64
-%   \xdef\vboxtohboxfactor{\withoutpt\the\scratchdimen}%
-%   \egroup}
-%
-% \protected\def\startvboxtohbox
-%  {\bgroup
-%   \setvboxtohbox
-%   \setbox\scratchbox\hbox\bgroup}
-%
-% \protected\def\stopvboxtohbox
-%   {\ifcase\vboxtohboxslack\else\hskip\zeropoint\s!minus\vboxtohboxslack\fi
-%    \egroup
-%    \dp\scratchbox\zeropoint
-%    \ht\scratchbox\vboxtohboxfactor\wd\scratchbox
-%    \box\scratchbox
-%    \egroup}
-
-% More modern:
-
-% \definesystemattribute[vboxtohboxseparator][public]
-
-%newbox\d_syst_boxes_vboxtohbox
-\newbox\d_syst_boxes_separator
-
-\permanent\protected\def\startvboxtohboxseparator
-  {\setbox\d_syst_boxes_separator\hbox attr \vboxtohboxseparatorattribute\plusone\bgroup}
-
-\permanent\protected\def\stopvboxtohboxseparator
-  {\egroup}
-
-\permanent\protected\def\startvboxtohbox
-  {\begingroup
-   \setbox\scratchbox\hbox\bgroup}
-
-\permanent\protected\def\stopvboxtohbox
-  {\ifvoid\d_syst_boxes_separator
-     \hskip\zeropoint\ifcase\vboxtohboxslack\else\s!minus\vboxtohboxslack\fi % we really need a skip
-   \else
-     \box\d_syst_boxes_separator
-   \fi
-   \egroup
-   \clf_hboxtovbox\scratchbox
-   \box\scratchbox
-   \endgroup}
-
-% A possible reconstruction:
-
-\permanent\protected\def\convertvboxtohbox
-  {\makehboxofhboxes
-   \setbox\scratchboxone\hpack{\unhbox\scratchboxone\removehboxes}% \hpack
-   \noindent\unhbox\scratchboxone\par}
-
-\permanent\protected\def\makehboxofhboxes
-  {\setbox\scratchboxone\emptyhbox
-   \loop % \doloop { .. \exitloop .. }
-     \setbox\scratchboxtwo\lastbox
-     \ifhbox\scratchboxtwo
-       \setbox\scratchboxone\hpack{\box\scratchboxtwo\unhbox\scratchboxone}%
-   \repeat}
-
-\permanent\protected\def\removehboxes
-  {\setbox\scratchboxone\lastbox
-   \ifhbox\scratchboxone
-     {\removehboxes}\unhbox\scratchboxone
-   \fi}
-
-% And one special for notes:
-
-\permanent\protected\def\starthboxestohbox
-  {\bgroup
-   \setbox\scratchbox\vbox\bgroup}
-
-\permanent\protected\def\stophboxestohbox
-  {\egroup
-   \clf_vboxlisttohbox\scratchbox\nextbox\dimexpr\hboxestohboxslack\relax
-   \dontleavehmode
-   \unhbox\nextbox
-   \removeunwantedspaces
-   \par
-   \egroup}
-
-%D \macros
-%D   {unhhbox}
-%D
-%D The next macro is used in typesetting inline headings. Let's first look at the
-%D macro and then show an example.
-
-\newbox   \unhhedbox
-\newbox   \hhbox
-\newdimen \lasthhboxwidth
-\newskip  \hhboxindent
-
-\permanent\protected\def\unhhbox#1\with#2%
-  {\bgroup
-   \nopenalties
-   \dontcomplain
-   \forgetall
-   \setbox\unhhedbox\vbox{\hskip\hhboxindent\strut\unhbox#1}% => \hsize
-   \doloop
-     {\setbox\hhbox\vsplit\unhhedbox to \lineheight
-      \ifvoid\unhhedbox
-        \setbox\hhbox\hbox{\strut\hboxofvbox\hhbox}% \hpack
-      \fi
-      \ht\hhbox\strutht
-      \dp\hhbox\strutdp
-      \ifzeropt\hhboxindent\else
-        \setbox\hhbox\hpack{\kern-\hhboxindent\box\hhbox}%
-        \hhboxindent\zeropoint
-      \fi
-      \global\lasthhboxwidth\wd\hhbox
-      #2\relax
-      \ifvoid\unhhedbox
-        \exitloop
-      \else
-        \hskip\zeropoint \s!plus \zeropoint
-      \fi}%
-   \egroup}
-
-\def\syst_boxes_hboxofvbox
-  {\setbox0\vpack{\unvbox\scratchcounter\global\setbox1\lastbox}%
-   \unhbox1
-   \egroup}
-
-\permanent\protected\def\hboxofvbox
-  {\bgroup
-   \afterassignment\syst_boxes_hboxofvbox
-   \scratchcounter=}
-
-%D This macro can be used to break a paragraph apart and treat each line seperately,
-%D for instance, making it clickable. The main complication is that we want to be
-%D able to continue the paragraph, something that's needed in the in line section
-%D headers.
-%D
-%D \startbuffer
-%D \setbox0=\hbox{\input tufte \relax}
-%D \setbox2=\hbox{\input knuth \relax}
-%D \unhhbox0\with{\ruledhbox{\box\hhbox}}
-%D \hskip1em plus 1em minus 1em
-%D \hhboxindent=\lasthhboxwidth
-%D \advance\hhboxindent by \lastskip
-%D \unhhbox2\with{\ruledhbox{\box\hhbox}}
-%D \stopbuffer
-%D
-%D \getbuffer
-%D
-%D This piece of text was typeset by saying:
-%D
-%D \typebuffer
-%D
-%D Not that nice a definition, but effective. Note the stretch we've build in the
-%D line that connects the two paragraphs.
-
-%D \macros
-%D   {doifcontent}
-%D
-%D When processing depends on the availability of content, one can give the next
-%D macro a try.
-%D
-%D \starttyping
-%D \doifcontent{pre content}{post content}{no content}\somebox
-%D \stoptyping
-%D
-%D Where \type {\somebox} is either a \type {\hbox} or \type {\vbox}. If the
-%D dimension of this box suggest some content, the resulting box is unboxed and
-%D surrounded by the first two arguments, else the third arguments is executed.
-
-\permanent\protected\def\doifcontent#1#2#3%
-  {\dowithnextbox
-     {\ifhbox\nextbox
-        \ifdim\wd\nextbox>\zeropoint
-          #1\unhbox\nextbox#2\relax
-        \else
-          #3\relax
-        \fi
-      \else
-        \ifdim\ht\nextbox>\zeropoint
-          #1\unvbox\nextbox#2\relax
-        \else
-          #3\relax
-        \fi
-      \fi}}
-
-%D So when we say:
-%D
-%D \startbuffer
-%D \doifcontent{[}{]}{}\hbox{content sensitive typesetting}
-%D
-%D \doifcontent{}{\page}{}\vbox{content sensitive typesetting}
-%D
-%D \doifcontent{}{}{\message{Didn't you forget something?}}\hbox{}
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D We get:
-%D
-%D \getbuffer
-%D
-%D Where the last call of course does not show up in this document, but definitely
-%D generates a confusing message.
-
-%D \macros
-%D   {processboxes}
-%D
-%D The next macro gobble boxes and is for instance used for overlays. First we show
-%D the general handler.
-
-\newbox\processbox % public : this is the one where \nextbox's end up in
-
-\permanent\protected\def\processboxes#1%
-  {\bgroup
-   \def\syst_boxes_process_indeed{#1}% #1 can be redefined halfway
-   \setbox\processbox\emptybox
-   \doifelsenextbgroup\syst_boxes_process_yes\syst_boxes_process_nop}
-
-\def\syst_boxes_process_yes
-  {\dowithnextboxcs\syst_boxes_process_content\hbox}
-
-\def\syst_boxes_process_content
-  {\removeunwantedspaces
-   \syst_boxes_process_indeed % takes \nextbox makes \processbox
-   \doifelsenextbgroup\syst_boxes_process_yes\syst_boxes_process_nop}
-
-\protected\def\syst_boxes_process_nop
-  {\removeunwantedspaces
-   \box\processbox
-   \egroup}
-
-%D \macros
-%D   {startoverlay}
-%D
-%D We can overlay boxes by saying:
-%D
-%D \startbuffer
-%D \startoverlay
-%D   {\framed{hans}}
-%D   {\framed[width=3cm]{ton}}
-%D   {\framed[height=2cm]{oeps}}
-%D \stopoverlay
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D shows up as:
-%D
-%D \leavevmode\getbuffer
-
-\permanent\def\boxisempty#1%
-  {\ifdim\wd#1=\zeropoint
-     \ifdim\ht#1=\zeropoint
-       \ifdim\dp#1=\zeropoint
-         \zerocount
-       \else
-         \plusone
-       \fi
-     \else
-       \plusone
-     \fi
-   \else
-     \plusone
-   \fi}
-
-\def\syst_boxes_overlay_process
-  {\ifcase\boxisempty\nextbox\else
-     \syst_boxes_overlay_process_indeed
-   \fi}
-
-\def\syst_boxes_overlay_process_indeed
-  {%\removeunwantedspaces % already done
-   \scratchdepth\dp\ifdim\dp\nextbox>\dp\processbox\nextbox\else\processbox\fi
-   \ifdim\ht\nextbox>\ht\processbox
-     \setbox\processbox\vpack to \ht\nextbox   {\dp\processbox\zeropoint\vss\box\processbox\vss}%
-   \else
-     \setbox\nextbox   \vpack to \ht\processbox{\dp\nextbox   \zeropoint\vss\box\nextbox   \vss}%
-   \fi
-   \dp\nextbox   \scratchdepth
-   \dp\processbox\scratchdepth
-   \scratchwidth\wd\ifdim\wd\nextbox>\wd\processbox\nextbox\else\processbox\fi
-   \setbox\processbox\hpack to \scratchwidth
-     {\hpack to \scratchwidth{\hss\box\processbox\hss}%
-      \kern-\scratchwidth
-      \hpack to \scratchwidth{\hss\box\nextbox   \hss}}}
-
-\permanent\protected\def\startoverlay
-  {\bgroup
-   \let\stopoverlay\egroup
-   \processboxes\syst_boxes_overlay_process}
-
-\let\stopoverlay\relax
-
-%D \macros
-%D   {fakebox}
-%D
-%D The next macro is a rather silly one, but saves space.
-%D
-%D \starttyping
-%D \hbox{\fakebox0}
-%D \stoptyping
-%D
-%D returns an empty box with the dimensions of the box specified, here being zero.
-
-\permanent\protected\def\fakebox
-  {\bgroup
-   \afterassignment\syst_boxes_fakebox_finish\scratchcounter}
-
-\def\syst_boxes_fakebox_finish
-  {\setbox\scratchbox\ifhbox\scratchcounter\emptyhbox\else\emptyvbox\fi
-   \wd\scratchbox\wd\scratchcounter
-   \ht\scratchbox\ht\scratchcounter
-   \dp\scratchbox\dp\scratchcounter
-   \box\scratchbox
-   \egroup}
-
-%D \macros
-%D   {lbox,rbox,cbox,tbox,bbox}
-%D
-%D Here are some convenient alternative box types:
-%D
-%D \starttyping
-%D \lbox{text ...}
-%D \cbox{text ...}
-%D \rbox{text ...}
-%D \stoptyping
-%D
-%D Are similar to \type {\vbox}, which means that they also accept something like
-%D \type {to 3cm}, but align to the left, middle and right. These box types can be
-%D used to typeset paragraphs.
-
-\def\syst_boxes_lrc_process#1%
-  {\bgroup
-   \forgetall
-   \enforced\let\\\endgraf
-   #1%
-   \let\nexttoken}
-
-\permanent\protected\def\lbox#1#{\vbox#1\syst_boxes_lrc_process\raggedleft  }
-\permanent\protected\def\cbox#1#{\vbox#1\syst_boxes_lrc_process\raggedcenter}
-\permanent\protected\def\rbox#1#{\vbox#1\syst_boxes_lrc_process\raggedright }
-
-\permanent\protected\def\ltop#1#{\vtop#1\syst_boxes_lrc_process\raggedleft  }
-\permanent\protected\def\ctop#1#{\vtop#1\syst_boxes_lrc_process\raggedcenter}
-\permanent\protected\def\rtop#1#{\vtop#1\syst_boxes_lrc_process\raggedright }
-
-%D The alternatives \type {\tbox} and \type {\bbox} can be used to properly align
-%D boxes, like in:
-%D
-%D \setupexternalfigures[directory={../sample}]
-%D \startbuffer
-%D \starttable[|||]
-%D \HL
-%D \VL \tbox{\externalfigure[cow][height=3cm,frame=on]} \VL top aligned    \VL\SR
-%D \HL
-%D \VL \bbox{\externalfigure[cow][height=3cm,frame=on]} \VL bottom aligned \VL\SR
-%D \HL
-%D \stoptable
-%D \stopbuffer
-%D
-%D \typebuffer
-%D
-%D The positioning depends on the strut settings:
-%D
-%D \getbuffer
-
-\permanent\protected\def\tbox{\hpack\bgroup\dowithnextboxcs\syst_boxes_tbox_finish\hbox}
-\permanent\protected\def\bbox{\hpack\bgroup\dowithnextboxcs\syst_boxes_bbox_finish\hbox}
-
-\def\syst_boxes_tbox_finish
-  {\scratchheight\ht\strutbox
-   \scratchdepth\dimexpr\htdp\nextbox-\scratchheight\relax
-   \ht\nextbox\scratchheight
-   \dp\nextbox\scratchdepth
-   \boxyoffset\nextbox-\scratchdepth
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_bbox_finish
-  {\scratchdepth\dp\strutbox
-   \scratchheight\dimexpr\htdp\nextbox-\scratchdepth\relax
-   \dp\nextbox\scratchdepth
-   \ht\nextbox\scratchheight
-   \boxyoffset\nextbox-\scratchdepth
-   \box\nextbox
-   \egroup}
-
-%D \macros
-%D   {lhbox,mhbox,rhbox}
-%D
-%D A few more boxes.
-
-\def\syst_boxes_lhbox{\hpack to \hsize{\box\nextbox\hss    }}
-\def\syst_boxes_mhbox{\hpack to \hsize{\hss\box\nextbox\hss}}
-\def\syst_boxes_rhbox{\hpack to \hsize{\hss\box\nextbox    }}
-
-\permanent\protected\def\lhbox{\dowithnextboxcs\syst_boxes_lhbox\hbox}
-\permanent\protected\def\mhbox{\dowithnextboxcs\syst_boxes_mhbox\hbox}
-\permanent\protected\def\rhbox{\dowithnextboxcs\syst_boxes_rhbox\hbox}
-
-\let\lefthbox \lhbox
-\let\midhbox  \mhbox
-\let\righthbox\rhbox
-
-%D \macros
-%D   {boxofsize}
-%D
-%D Sometimes we need to construct a box with a height or width made up of several
-%D dimensions. Instead of cumbersome additions, we can use:
-%D
-%D \starttyping
-%D \boxofsize \vbox 10cm 3cm -5cm {the text to be typeset}
-%D \stoptyping
-%D
-%D This example demonstrates that one can use positive and negative values.
-%D Dimension registers are also accepted.
-
-\newdimen\sizeofbox
-
-\permanent\protected\def\boxofsize#1%
-  {\bgroup
-   \sizeofbox\zeropoint
-   \scratchdimen\zeropoint
-   \def\docommand
-     {\advance\sizeofbox\scratchdimen
-      \futurelet\nexttoken\dodocommand}%
-   \def\dodocommand
-     {\ifx\nexttoken\bgroup
-        \expanded{\egroup#1 to \the\sizeofbox}%
-      \else
-        \expandafter\afterassignment\expandafter\docommand\expandafter\scratchdimen
-      \fi}%
-   \docommand}
-
-%D Some new, still undocumented features:
-
-% limitatetext -> beter {text} als laatste !!
-%
-% \limitvbox
-% \limithbox
-
-\permanent\protected\def\limitatelines#1#2% size sentinel
-  {\dowithnextbox
-     {\scratchdimen#1\hsize
-      \ifdim\wd\nextbox>\scratchdimen
-        \setbox\nextbox\hbox
-          {\advance\scratchdimen -.1\hsize
-           \limitatetext{\unhbox\nextbox}{\scratchdimen}{\nobreak#2}}%
-      \fi
-      \unhbox\nextbox}
-     \hbox}
-
-\permanent\protected\def\fittoptobaselinegrid % weg hier
-  {\dowithnextbox
-     {\bgroup
-      \par
-      \scratchdimen\ht\nextbox
-      \ht\nextbox\strutht
-      \dp\nextbox\strutdp
-      \hpack{\box\nextbox}
-      \prevdepth\strutdp
-      \doloop
-        {\advance\scratchdimen -\lineheight
-         \ifdim\scratchdimen<\zeropoint
-           \exitloop
-         \else
-           \nobreak
-           \hpack{\strut}
-         \fi}
-      \egroup}
-     \vbox}
-
-%D Some more undocumented macros (used in m-chart).
-
-\newif\iftraceboxplacement % \traceboxplacementtrue
-
-\newbox\fakedboxcursor
-
-\setbox\fakedboxcursor\hpack
-  {\vrule\s!width\zeropoint\s!height\zeropoint\s!depth\zeropoint}
-
-\permanent\protected\def\boxcursor % overloaded in core-vis
-  {\iftraceboxplacement
-     \bgroup
-     \scratchdimen2\onepoint
-     \setbox\scratchbox\hpack to \zeropoint
-       {\hss
-        \vrule
-          \s!width \scratchdimen
-          \s!height\scratchdimen
-          \s!depth \scratchdimen
-        \hss}%
-     \smashedbox\scratchbox
-     \egroup
-   \else
-     \copy\fakedboxcursor
-   \fi}
-
-\permanent\protected\def\placedbox
-  {\iftraceboxplacement\ruledhbox\else\hbox\fi}
-
-\newdimen\boxoffset
-\newdimen\boxhdisplacement
-\newdimen\boxvdisplacement
-
-\permanent\protected\def\rightbox      {\hpack\bgroup\dowithnextboxcs\syst_boxes_rightbox_finish      \placedbox}
-\permanent\protected\def\leftbox       {\hpack\bgroup\dowithnextboxcs\syst_boxes_leftbox_finish       \placedbox}
-\permanent\protected\def\topbox        {\hpack\bgroup\dowithnextboxcs\syst_boxes_topbox_finish        \placedbox}
-\permanent\protected\def\bottombox     {\hpack\bgroup\dowithnextboxcs\syst_boxes_bottombox_finish     \placedbox}
-\permanent\protected\def\lefttopbox    {\hpack\bgroup\dowithnextboxcs\syst_boxes_lefttopbox_finish    \placedbox}
-\permanent\protected\def\righttopbox   {\hpack\bgroup\dowithnextboxcs\syst_boxes_righttopbox_finish   \placedbox}
-\permanent\protected\def\leftbottombox {\hpack\bgroup\dowithnextboxcs\syst_boxes_leftbottombox_finish \placedbox}
-\permanent\protected\def\rightbottombox{\hpack\bgroup\dowithnextboxcs\syst_boxes_rightbottombox_finish\placedbox}
-
-\let\topleftbox    \lefttopbox
-\let\toprightbox   \righttopbox
-\let\bottomleftbox \leftbottombox
-\let\bottomrightbox\rightbottombox
-
-\def\syst_boxes_rightbox_finish
-  {\global\boxhdisplacement\boxoffset
-   \global\boxvdisplacement.5\dimexpr\ht\nextbox-\dp\nextbox\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_leftbox_finish
-  {\global\boxhdisplacement\dimexpr-\wd\nextbox-\boxoffset\relax
-   \global\boxvdisplacement.5\dimexpr\ht\nextbox-\dp\nextbox\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_topbox_finish
-  {\global\boxhdisplacement-.5\wd\nextbox
-   \global\boxvdisplacement\dimexpr-\dp\nextbox-\boxoffset\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_bottombox_finish
-  {\global\boxhdisplacement-.5\wd\nextbox
-   \global\boxvdisplacement\dimexpr\ht\nextbox+\boxoffset\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_lefttopbox_finish
-  {\global\boxhdisplacement\dimexpr-\wd\nextbox-\boxoffset\relax
-   \global\boxvdisplacement\dimexpr-\dp\nextbox-\boxoffset\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_righttopbox_finish
-  {\global\boxhdisplacement\boxoffset
-   \global\boxvdisplacement\dimexpr-\dp\nextbox-\boxoffset\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_leftbottombox_finish
-  {\global\boxhdisplacement\dimexpr-\wd\nextbox-\boxoffset\relax
-   \global\boxvdisplacement\dimexpr\ht\nextbox+\boxoffset\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_rightbottombox_finish
-  {\global\boxhdisplacement\boxoffset
-   \global\boxvdisplacement\dimexpr\ht\nextbox+\boxoffset\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\permanent\protected\def\middlebox        {\hpack\bgroup\dowithnextboxcs\syst_boxes_middlebox_finish        \placedbox}
-\permanent\protected\def\baselinemiddlebox{\hpack\bgroup\dowithnextboxcs\syst_boxes_baselinemiddlebox_finish\placedbox}
-\permanent\protected\def\baselineleftbox  {\hpack\bgroup\dowithnextboxcs\syst_boxes_baselineleftbox_finish  \placedbox}
-\permanent\protected\def\baselinerightbox {\hpack\bgroup\dowithnextboxcs\syst_boxes_baselinerightbox_finish \placedbox}
-
-\def\syst_boxes_middlebox_finish
-  {\global\boxhdisplacement-.5\wd\nextbox
-   \global\boxvdisplacement.5\dimexpr\ht\nextbox-\dp\nextbox\relax
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_baselinemiddlebox_finish
-  {\global\boxhdisplacement\dimexpr-.5\wd\nextbox-\boxoffset\relax
-   \global\boxvdisplacement-\boxoffset
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_baselineleftbox_finish
-  {\global\boxhdisplacement\dimexpr-\wd\nextbox-\boxoffset\relax
-   \global\boxvdisplacement-\boxoffset
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_baselinerightbox_finish
-  {\global\boxhdisplacement\boxoffset
-   \global\boxvdisplacement-\boxoffset
-   \boxcursor
-   \boxxmove\nextbox \boxhdisplacement
-   \boxymove\nextbox-\boxvdisplacement
-   \box\nextbox
-   \egroup}
-
-%D \macros
-%D   {obox}
-%D
-%D Experimental, not yet frozen:
-
-\permanent\protected\def\lrtbbox#1#2#3#4% l r t b
-  {\bgroup
-   \dowithnextboxcontent
-     {\advance\hsize-#1\advance\hsize-#2\relax
-      \advance\vsize-#3\advance\vsize-#4\relax}
-     {\forgetall\vpack to \vsize{\vskip#3\hpack to \hsize{\hskip#1\box\nextbox\hss}\vss}\egroup}
-     \vbox}
-
-%D \macros
-%D   {toplinebox}
-%D
-%D See core-tbl.tex for an example of its usage:
-
-\permanent\protected\def\toplinebox
-  {\dowithnextboxcs\syst_boxes_toplinebox_finish\tbox}
-
-\def\syst_boxes_toplinebox_finish
-  {\ifdim\dp\nextbox>\strutdepth
-     \scratchdimen\dp\nextbox
-     \advance\scratchdimen-\strutdepth
-     \getnoflines\scratchdimen
-     \struttedbox{\box\nextbox}%
-     \dorecurse\noflines\verticalstrut
-   \else
-     \box\nextbox
-   \fi}
-
-%D \macros
-%D   {initializeboxstack,savebox,foundbox}
-%D
-%D At the cost of some memory, but saving box registers, we have implemented a box
-%D repository.
-%D
-%D \starttyping
-%D \initializeboxstack{one}
-%D
-%D \savebox{one}{a}{test a}
-%D \savebox{one}{p}{test p}
-%D \savebox{one}{q}{test q}
-%D
-%D \hbox{a:\foundbox{one}{a}} \par
-%D \hbox{q:\foundbox{one}{q}} \par
-%D \hbox{p:\foundbox{one}{p}} \par
-%D \hbox{x:\foundbox{one}{x}} \par
-%D \hbox{y:\foundbox{two}{a}} \par
-%D \stoptyping
-
-%D Kind of obsolete:
-
-\installcorenamespace {stackbox}
-\installcorenamespace {stacklst}
-
-\permanent\protected\def\setstackbox#1#2%
-  {\ifcsname\??stackbox#1:#2\endcsname\else
-     \expandafter\newbox\csname\??stackbox#1:#2\endcsname
-   \fi
-   \global\setbox\csname\??stackbox#1:#2\endcsname\vbox}
-
-\permanent\protected\def\initializeboxstack#1%
-  {\def\docommand##1{\setstackbox{#1}{##1}{}}%
-   \ifcsname\??stacklst#1\endcsname
-     \expandafter\processcommacommand\expandafter[\lastnamedcs]\docommand
-   \fi
-   \letgvalueempty{\??stacklst#1}}
-
-\permanent\protected\def\savebox#1#2% stack name
-  {% beware, \setxvalue defines the cs beforehand so we cannot use the
-   % test inside the { }
-   \ifcsname\??stacklst#1\endcsname
-    %\setxvalue{\??stacklst#1}{\csname\??stacklst#1\endcsname,#2}%
-     \expandafter\xdef\csname\??stacklst#1\expandafter\endcsname\expandafter{\lastnamedcs,#2}%
-   \else
-     \expandafter\xdef\csname\??stacklst#1\endcsname{#2}%
-   \fi
-   \setstackbox{#1}{#2}}
-
-\permanent\protected\def\flushbox#1#2% unwrapped
-  {\ifcsname\??stackbox#1:#2\endcsname
-     \box\lastnamedcs
-   \else
-     \emptybox
-   \fi}
-
-\permanent\protected\def\restorebox#1#2% unwrapped
-  {\ifcsname\??stackbox#1:#2\endcsname
-     \copy\lastnamedcs
-   \else
-     \emptybox
-   \fi}
-
-\permanent\protected\def\foundbox#1#2% wrapped
-  {\vpack
-     {\ifcsname\??stackbox#1:#2\endcsname
-        \copy\lastnamedcs
-      \fi}}
-
-\permanent\protected\def\doifelsebox#1#2%
-  {\ifcsname\??stackbox#1:#2\endcsname
-     \ifvoid\lastnamedcs
-       \doubleexpandafter\secondoftwoarguments
-     \else
-       \doubleexpandafter\firstoftwoarguments
-     \fi
-   \else
-     \expandafter\secondoftwoarguments
-   \fi}
-
-\let\doifboxelse\doifelsebox
-
-%D This one is cheaper (the above is no longer used that much):
-
-\installcorenamespace {boxstack}
-
-\newcount\c_syst_boxes_stack
-
-\mutable\let\b_syst_boxes_stack\relax
-
-\protected\def\syst_boxes_stack_allocate
-  {\newbox\b_syst_boxes_stack
-   \letcsname\??boxstack\number\c_syst_boxes_stack\endcsname\b_syst_boxes_stack}
-
-\protected\def\syst_boxes_push#1#2%
-  {\global\advance\c_syst_boxes_stack\plusone
-   \expandafter\let\expandafter\b_syst_boxes_stack\csname\??boxstack\number\c_syst_boxes_stack\endcsname
-   \ifx\b_syst_boxes_stack\relax % cheaper then csname check as in most cases it's defined
-      \syst_boxes_stack_allocate
-   \fi
-   #1\setbox\b_syst_boxes_stack\box#2\relax}
-
-\protected\def\syst_boxes_pop#1#2%
-  {#1\setbox#2\box\csname\??boxstack\number\c_syst_boxes_stack\endcsname
-   \global\advance\c_syst_boxes_stack\minusone}
-
-\permanent\protected\def\localpushbox {\syst_boxes_push\relax}
-\permanent\protected\def\localpopbox  {\syst_boxes_pop \relax}
-
-\permanent\protected\def\globalpushbox{\syst_boxes_push\global}
-\permanent\protected\def\globalpopbox {\syst_boxes_pop \global}
-
-%D And here is a more modern one (not yet in i-*):
-%D
-%D \starttyping
-%D \dorecurse {100} {
-%D     \setbox\zerocount\hbox{test \recurselevel}
-%D     \putboxincache{foo}{\recurselevel}\zerocount
-%D     \copyboxfromcache{foo}{\recurselevel}\zerocount
-%D     \iftrue
-%D         \setbox\zerocount\hbox{\directboxfromcache{foo}{\recurselevel}}%
-%D     \else
-%D         \getboxfromcache{foo}{\recurselevel}\zerocount
-%D     \fi
-%D }
-%D \resetboxesincache{foo}
-%D \stoptyping
-
-\permanent\protected\def\putboxincache       #1#2#3{\clf_putboxincache         {#1}{#2}#3\relax}
-\permanent\protected\def\getboxfromcache     #1#2#3{\clf_getboxfromcache       {#1}{#2}#3\relax}
-\permanent\protected\def\doifelseboxincache    #1#2{\clf_doifelseboxincache    {#1}{#2}}
-\permanent\protected\def\copyboxfromcache    #1#2#3{\clf_copyboxfromcache      {#1}{#2}#3\relax}
-\permanent\protected\def\directboxfromcache    #1#2{\clf_directboxfromcache    {#1}{#2}}
-\permanent\protected\def\directcopyboxfromcache#1#2{\clf_directcopyboxfromcache{#1}{#2}}
-\permanent\protected\def\resetboxesincache       #1{\clf_resetboxesincache     {#1}}
-
-\permanent\protected\def\putnextboxincache#1#2%
-  {\dowithnextbox{\putboxincache{#1}{#2}\nextbox}}
-
-%D \macros
-%D   {removedepth, obeydepth}
-%D
-%D While \type {\removedepth} removes the preceding depth, \type {\obeydepth} makes
-%D sure we have depth. Both macros leave the \type {\prevdepth} untouched.
-
-\permanent\protected\def\removedepth
-  {\ifvmode
-     \ifdim\prevdepth>\zeropoint
-       \kern-\prevdepth
-     \fi
-   \fi}
-
-\permanent\protected\def\obeydepth
-  {\par % watch out for changes in math formulas
-   \ifvmode\ifdim\prevdepth<\zeropoint\orelse\ifdim\prevdepth<\strutdp
-     \kern\dimexpr\strutdp-\prevdepth\relax
-     \prevdepth\strutdp
-   \fi\fi}
-
-\permanent\protected\def\undepthed
-  {\dowithnextbox{\dp\nextbox\zeropoint\box\nextbox}\hbox}
-
-%D \macros
-%D   {removebottomthings, removelastskip}
-%D
-%D A funny (but rather stupid) one, plus a redefinition.
-
-\permanent\protected\def\removebottomthings
-  {\dorecurse\plusfive{\unskip\unkern\unpenalty}}
-
-\permanent\protected\def\removelastskip % \ifvmode the plain tex one \fi, overloaded to \permanent in spac-ver
-  {\ifvmode\ifzeropt\lastskip\else\vskip-\lastskip\fi\fi}
-
-%D \macros
-%D   {makestrutofbox}
-%D
-%D This macro sets the dimensions of a box to those of a strut. Sort of obsolete so
-%D it will go away.
-
-\permanent\protected\def\makestrutofbox % not used
-  {\afterassignment\syst_boxes_makestrutofbox\c_boxes_register}
-
-\def\syst_boxes_makestrutofbox
-  {\ht\c_boxes_register\strutht
-   \dp\c_boxes_register\strutdp
-   \wd\c_boxes_register\zeropoint}
-
-%D \macros
-%D   {raisebox,lowerbox}
-%D
-%D Some more box stuff, related to positioning (under construction). Nice stuff for
-%D a tips and tricks maps article.
-%D
-%D \starttyping
-%D \raisebox{100pt}\hbox{test}
-%D \hsmash{\raisebox{100pt}\hbox{test}}
-%D \stoptyping
-
-\permanent\protected\def\raisebox#1{\bgroup\afterassignment\syst_boxes_raise_indeed\scratchdimen#1} % so both 10pt and {10pt} is accepted
-\permanent\protected\def\lowerbox#1{\bgroup\afterassignment\syst_boxes_lower_indeed\scratchdimen#1} % so both 10pt and {10pt} is accepted
-
-\def\syst_boxes_raise_indeed{\dowithnextboxcs\syst_boxes_raise_finish}
-\def\syst_boxes_lower_indeed{\dowithnextboxcs\syst_boxes_lower_finish}
-
-\def\syst_boxes_raise_finish
-  {\boxyoffset\nextbox\scratchdimen
-   \ht\nextbox\strutht
-   \dp\nextbox\strutdp
-   \box\nextbox
-   \egroup}
-
-\def\syst_boxes_lower_finish
-  {\boxyoffset\nextbox-\scratchdimen
-   \ht\nextbox\strutht
-   \dp\nextbox\strutdp
-   \box\nextbox
-   \egroup}
-
-% vcenter in text, we kunnen vcenter overloaden
-
-\permanent\protected\def\halfwaybox
-  {\hpack\bgroup
-   \dowithnextboxcs\syst_boxes_halfwaybox_finish\hbox}
-
-\def\syst_boxes_halfwaybox_finish
-  {\dp\nextbox\zeropoint
-   \lower.5\ht\nextbox\box\nextbox
-   \egroup}
-
-\permanent\protected\def\depthonlybox
-  {\tpack\bgroup
-   \dowithnextboxcs\syst_boxes_depthonlybox_finish\vbox}
-
-\def\syst_boxes_depthonlybox_finish
-  {\hsize\wd\nextbox
-   \kern\zeropoint\box\nextbox
-   \egroup}
-
-%D New:
-
-\permanent\def\setdimentoatleast#1#2{\ifdim#1>\zeropoint\else#1=#2\fi}
-\permanent\def\setdimentoatmost #1#2{\ifdim#1>#2\relax  \else#1=#2\fi}
-
-%D And even rawer:
-
-\let\naturalvcenter\normalvtop % will go away
-
-% \appendtoks \let\vcenter\normalvcenter \to \everymathematics
-
-%D \macros
-%D   {frozenhbox}
-%D
-%D A not so well unhboxable box can be made with:
-
-\permanent\protected\def\frozenhbox
-  {\hpack\bgroup
-   \dowithnextboxcs\syst_boxes_frozenhbox_finish\hbox}
-
-\def\syst_boxes_frozenhbox_finish
-  {\hpack{\hpack{\box\nextbox}}%
-   \egroup}
-
-%D \macros
-%D   {setboxllx,setboxlly,gsetboxllx,gsetboxlly,getboxllx,getboxlly}
-%D
-%D A prelude to an extended \TEX\ feature:
-
-\installcorenamespace {box_x}
-\installcorenamespace {box_y}
-
-\permanent\protected\def\setboxllx #1#2{\edefcsname\??box_x\number#1\endcsname{\the\dimexpr#2\relax}}
-\permanent\protected\def\setboxlly #1#2{\edefcsname\??box_y\number#1\endcsname{\the\dimexpr#2\relax}}
-
-\permanent\protected\def\gsetboxllx#1#2{\global\edefcsname\??box_x\number#1\endcsname{\the\dimexpr#2\relax}}
-\permanent\protected\def\gsetboxlly#1#2{\global\edefcsname\??box_y\number#1\endcsname{\the\dimexpr#2\relax}}
-
-\permanent\def\getboxllx#1{\ifcsname\??box_x\number#1\endcsname\lastnamedcs\else\zeropoint\fi}
-\permanent\def\getboxlly#1{\ifcsname\??box_y\number#1\endcsname\lastnamedcs\else\zeropoint\fi}
-
-\permanent\def\directgetboxllx#1{\csname\??box_x\number#1\endcsname} % use when sure existence
-\permanent\def\directgetboxlly#1{\csname\??box_y\number#1\endcsname} % use when sure existence
-
-%D \macros
-%D   {shownextbox}
-%D
-%D Handy for tracing
-%D
-%D \starttyping
-%D \shownextbox\vbox{test}
-%D \shownextbox\vbox{test\endgraf}
-%D \shownextbox\vbox{test\endgraf\strut\endgraf}
-%D \shownextbox\vbox{test\endgraf\thinrule}
-%D \shownextbox\vbox{\setupwhitespace[big]test\endgraf\thinrule}
-%D \stoptyping
-
-\permanent\protected\def\shownextbox % seldom used
-  {\dowithnextbox
-     {\bgroup
-      \showboxbreadth\maxdimen
-      \showboxdepth  \maxdimen
-      \scratchcounter\interactionmode
-      \batchmode
-      \showbox\nextbox
-      \box\nextbox
-      \interactionmode\scratchcounter
-      \egroup}}
-
-\permanent\protected\def\spreadhbox#1% rebuilds \hbox{<box><hss><box><hss><box>}
-  {\bgroup
-   \ifhbox#1\relax
-     \setbox\scratchboxtwo\emptybox
-     \unhbox#1%
-     \doloop
-       {\unpenalty\unskip\unpenalty\unskip\unpenalty\unskip
-        \setbox\scratchboxone\lastbox
-        \ifvoid\scratchboxone
-          \exitloop
-        \else
-          \setbox\scratchboxtwo\hbox
-            {\ifhbox\scratchboxone \spreadhbox\scratchboxone\else\box\scratchboxone\fi
-             \ifvoid\scratchboxtwo \else\hss\unhbox\scratchboxtwo\fi}%
-        \fi}%
-     \ifvoid\scratchboxtwo\else\unhbox\scratchboxtwo\fi
-   \else
-     \box#1%
-   \fi
-   \egroup}
-
-% Why not ...
-
-\showboxbreadth\plusthousand
-\showboxdepth  \plusthousand
-
-%D Moved from cont-new:
-%D
-%D \starttyping
-%D \minimalhbox 100pt {test}
-%D \stoptyping
-
-\permanent\protected\def\minimalhbox#1#%
-  {\dowithnextbox
-     {\bgroup
-      \setbox\scratchbox\hpack#1{\hss}%
-      \ifdim\wd\nextbox<\wd\scratchbox\wd\nextbox\wd\scratchbox\fi
-      \box\nextbox
-      \egroup}
-     \hbox}
-
-%D A bit dirty:
-
-\permanent\protected\def\nodestostring#1#2% more tolerant for #2=\cs
-  {\begingroup
-   \setbox\nextbox\hbox{#2}%
-   \normalexpanded{\endgroup\edef\noexpand#1{\clf_boxtostring\nextbox}}}
-
-%D Even more dirty:
-
-\let\hyphenatedhbox\hbox
-
-%D We can do this:
-%D
-%D \starttyping
-%D \setbox0\hbox to 10cm{foo} \setbox2\hbox{\unhbox0} \the\wd2
-%D \stoptyping
-%D
-%D But this saves a copy (and hpack pass):
-%D
-%D \starttyping
-%D \setbox0\hbox to 10cm{foo} \the\naturalwd0
-%D \stoptyping
-
-\newdimen\lastnaturalboxwd
-\newdimen\lastnaturalboxht
-\newdimen\lastnaturalboxdp
-
-\let\getnaturaldimensions\clf_getnaturaldimensions % sets three dimensions
-\let\naturalwd           \clf_naturalwd            % calculates and returns wd
-
-\let\getnaturalwd\clf_getnaturalwd % no intermediate
-\let\setnaturalwd\clf_setnaturalwd % no intermediate
-
-\permanent\protected\def\doifelserighttoleftinbox{\clf_doifelserighttoleftinbox}
-
-\let\doifrighttoleftinboxelse\doifelserighttoleftinbox
-
-%D New, used in high/low:
-
-\definesystemattribute [runningtext] [public]
-
-\permanent\protected\def\runninghbox{\hbox attr \runningtextattribute \fontid\font} % not yet in i-*
-
-%D To complement lua (yet undocumented):
-
-\permanent\protected\def\beginhbox{\hbox\bgroup}  \let\endhbox\egroup
-\permanent\protected\def\beginvbox{\vbox\bgroup}  \let\endvbox\egroup
-\permanent\protected\def\beginvtop{\vtop\bgroup}  \let\endvtop\egroup
-
-\permanent\protected\def\sethboxregister#1{\setbox#1\hbox}
-\permanent\protected\def\setvboxregister#1{\setbox#1\vbox}
-\permanent\protected\def\setvtopregister#1{\setbox#1\vtop}
-
-\permanent\protected\def\flushboxregister#1{\box\numexpr#1\relax}
-
-\permanent\protected\def\starthboxregister#1{\setbox#1\hbox\bgroup}  \let\stophboxregister\egroup
-\permanent\protected\def\startvboxregister#1{\setbox#1\vbox\bgroup}  \let\stopvboxregister\egroup
-\permanent\protected\def\startvtopregister#1{\setbox#1\vtop\bgroup}  \let\stopvtopregister\egroup
-
-%D For whatever third party package needs it:
-%D
-%D \starttyping
-%D \newlocalbox\BoxOne
-%D \newlocalbox\BoxTwo
-%D
-%D \setbox\BoxOne\hbox{Box One}
-%D \setbox\BoxTwo\hbox{Box Two}
-%D
-%D [\box\BoxTwo] [\box\BoxOne]
-%D \stoptyping
-
-\installcorenamespace{localbox}
-
-\permanent\protected\def\newlocalbox#1%
-  {\expandafter\let\expandafter#1\csname\??localbox\string#1\endcsname
-   \ifx#1\relax
-     \syst_aux_new_localbox#1%
-   \fi}
-
-\def\syst_aux_new_localbox#1%
-  {\expandafter\newbox\csname\??localbox\string#1\endcsname
-   \newlocalbox#1}
-
-%D Who knows when this comes in handy:
-
-\permanent\protected\def\lastlinewidth{\dimexpr\clf_lastlinewidth\scaledpoint\relax}
-
-%D Keep as reference:
-
-% \protected\def\tightvbox{\dowithnextbox{\dp\nextbox\zeropoint\box\nextbox}\vbox}
-% \protected\def\tightvtop{\dowithnextbox{\ht\nextbox\zeropoint\box\nextbox}\vtop}
-
-%D This one keeps dimensions and sets the shift field (and so it's more for testing
-%D than for real usage):
-
-\permanent\protected\def\shiftbox  {\clf_shiftbox}
-\permanent\protected\def\vpackbox  {\clf_vpackbox}
-\permanent\protected\def\hpackbox  {\clf_hpackbox}
-\permanent\protected\def\vpackedbox{\clf_vpackedbox}
-\permanent\protected\def\hpackedbox{\clf_hpackedbox}
-
-%D This one has been moved from a 2 decade old file. It makes something boxed
-%D sit on the baseline.
-
-\protected\def\linebox
-  {\hpack\bgroup\dowithnextbox
-     {\scratchdimen\dimexpr\dimexpr\htdp\nextbox-\lineheight\relax/2+\dp\strutbox\relax
-      \setbox\nextbox\hpack{\lower\scratchdimen\box\nextbox}%
-      \ht\nextbox\ht\strutbox
-      \dp\nextbox\dp\strutbox
-      \box\nextbox
-      \egroup}
-     \hbox}
-
-%D \macros
-%D   {widthuptohere}
-%D
-%D Implemented at the \LUA\ end:
-%D
-%D \startbuffer
-%D widthuptohere:\the\widthuptohere\crlf
-%D widthuptohere : \the\widthuptohere (space without stretch or shrink!)
-%D \stopbuffer
-%D
-%D \typebuffer \blank \getbuffer \blank
-%D
-%D Implemented elsewhere:
-%D
-%D \starttyping
-%D \boxlines    <box>
-%D \boxline     <box> <line>
-%D \copyboxline <box> <line>
-%D \setboxline  <box> <line>
-%D \boxlineht   <box> <line> [<dimen>]
-%D \boxlinedp   <box> <line> [<dimen>]
-%D \boxlinewd   <box> <line> [<dimen>]
-%D \boxlinels   <box> <line>
-%D \boxliners   <box> <line>
-%D \boxlinelh   <box> <line>
-%D \boxlinerh   <box> <line>
-%D \boxlinelp   <box> <line>
-%D \boxlinerp   <box> <line>
-%D \boxlinein   <box> <line>
-%D \boxrangeht  <box> <first line> <last line>
-%D \boxrangedp  <box> <first line> <last line>
-%D \boxrangewd  <box> <first line> <last line>
-%D \stoptyping
-
-% To be discussed with ws.
-%
-% \installcorenamespace{namedboxes}
-%
-% \protected\def\newnamedbox#1%
-%   {\ifcsname\??namedboxes#1\endcsname\else
-%      \expandafter\newbox\csname\??namedboxes#1\endcsname
-%    \fi}
-%
-% \protected\def\namedbox#1{\csname\??namedboxes#1\endcsname}
-
-%D Implemented elsewhere:
-%D
-%D \startbuffer
-%D \setbox0\hbox{test \footnote{test}} (\prelistbox0) (\postlistbox0)
-%D \setprelistbox0\hbox{BEFORE} \setpostlistbox0\hbox{AFTER}
-%D \box0
-%D \stopbuffer
-%D
-%D \typebuffer \blank \getbuffer \blank
-%D
-%D \starttyping
-%D \prelistbox     <box>
-%D \postlistbox    <box>
-%D \prelistcopy    <box>
-%D \postlistcopy   <box>
-%D \setprelistbox  <box> <hbox|vbox|vtop|somebox>
-%D \setpostlistbox <box> <hbox|vbox|vtop|somebox>
-%D \stoptyping
-
-\protect \endinput
-
-% a bit of test code:
-
-% \hbox \bgroup
-%     \ruledvbox                {\hbox{\strut gans}}
-%     \ruledvbox to \lineheight {\hbox{\strut gans}}
-%     \ruledvbox to \lineheight {\hbox       {gans}}
-%     \ruledvbox to \strutheight{\hbox       {gans}}
-%     \ruledvbox to \strutheight{\hbox{\strut gans}}
-%     \ruledvbox to \strutheight{\vss\hbox{gans}}
-% \egroup
-
-% to be considered
-
-% \startluacode
-%
-%     local spacer = lpeg.patterns.spacer
-%
-%     function commands.withwords(command,str)
-%         if str then
-%             command = command or "ruledhbox"
-%             local done = false
-%             local function apply(s)
-%                 if done then
-%                     context.space()
-%                     done = true
-%                 else
-%                     context.dontleavehmode()
-%                 end
-%                 context[command](s)
-%             end
-%             lpeg.match(lpeg.splitter(spacer,apply),str)
-%         end
-%
-%     end
-%
-% \stopluacode
-%
-% \unprotect
-%
-% \protected\def\withwordsinstring#1#2% command str
-%   {\ctxcommand{withwords(\!!bs#1\!!es,\!!bs#2\!!es)}}
-%
-% \protected\def\withwordsinfile#1#2% command name
-%   {\ctxcommand{withwords(\!!bs#1\!!es,io.loaddata(resolvers.findfile("#2")))}}
-%
-% \protect
-%
-% \starttext
-%
-%     \defineframed[colored][foregroundcolor=red,foregroundstyle=\bfc\underbar,location=low]
-%
-%     \withwordsinstring{colored}{bla bla}
-%     \withwordsinfile{colored}{ward.tex}
-%
-% \stoptext