%D \module
%D   [       file=anch-pos, % was core-pos
%D        version=1999.08.01,
%D          title=\CONTEXT\ Anchoring Macros,
%D       subtitle=Positioning Support,
%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.

% needs a cleanup, things may change; we also need to move the mp
% related code to meta-pos

% shorter tags, ..:achtergrond:.. etc in pos actions
% dubbele text- * pos's eruit

% class pos -> als gelijk aan vorige, dan niet niet definieren
% en erven, maw:
%
% 1 -> opslaan
% 2 -> undef, dus == prev
% 3 -> undef, dus == prev
% 4 -> opslaan

\writestatus{loading}{ConTeXt Anchoring Macros / Positioning}

% saveposition     : tag page x y
% savepositionwhd  : tag page x y w h d
% savepositionplus : tag page x y w h d list
%
% at some point (when we no longer share code) we will move to numbers
% do that we have less garbage collection and hashing
%
% the global table _ptbs_ is equivalent to job.positions.tobesaved
% the global table _pcol_ is equivalent to job.positions.collected
%
% btw, using a function is more efficient than passing longer code
% snippets to ctxlua

\registerctxluafile{anch-pos}{1.001}

% todo: topskip als optie voor eerste regel achtergrond
% todo: build pos layers on top of layers
% todo: positionlayer pos van text-1 etc delen

%D Although \TEX\ has a rather powerful channel to the outside
%D world, called \type {\special}, real communication with
%D other programs is complicated by the fact that no positional
%D information is available. Mid 1999, I discussed this with
%D \THANH, the author of \PDFTEX, and after some experiments,
%D \PDFTEX\ was extended with a simple but effective mechanism,
%D that provided positional information. The interesting
%D thought is that, although \TEX\ is frozen, similar
%D functionality could have been achieved with \type
%D {\specials} and an additional \DVI\ postprocessor.
%D
%D Since we want to be as compatible as can be, \CONTEXT\ will
%D support both methods, although the development is primarily
%D driven by the \PDFTEX\ way of doing things. Since the
%D mechanism is basically not limited to one application, for
%D the moment we stick to building the functionality around one
%D \CONTEXT\ special command, but at the same time we keep our
%D eyes open for extensions in other directions.
%D
%D A question that may arise when one reads this module, is to
%D what extend these macros are generic, in the sense that they
%D could be collected in a support module instead of a core
%D module. Since the mechanism described here will closely
%D cooperate with the \METAPOST\ support built in \CONTEXT,
%D which in turn will be tightly integrated with the \CONTEXT\
%D overlay mechanisms, I decided to write a core module instead
%D of a support one. This makes even more sense, when one takes
%D into account that this kind of support depends on special
%D drivers.

\unprotect

%D The first application of positional information was embedded
%D graphics. Since we are interacting with text, it made sense
%D to take the current line height and depth into account too.
%D This is why we have two basic position macros: one for
%D simple positions, and one for boxes.
%D
%D We could have sticked to one special, and actually did so in
%D earlier experiments, but for convenience, as well for
%D clearness, we now have two alternatives. This approach will
%D save us quite some bytes when storing large quantities of
%D positional information. We save as less information as
%D needed, that is, we save no dimensions, in a \METAPOST\
%D friendly way.
%D
%D The three specials involved are:
%D
%D \starttyping
%D \dosetposition          {identifier}
%D \dosetpositionwhd       {identifier} {width} {height} {depth}
%D \dosetpositionplus      {identifier} {width} {height} {depth} {list}
%D \dosetpositionpapersize {width} {height}
%D \stoptyping
%D
%D Positions are either generated at a delayed write time
%D (in \PDFTEX), or derived from the dvi file. The actual
%D method is implemented in a special driver. If needed, the
%D driver can fall back on the following macros.

% \def\dolazysaveposition            #1#2#3#4{\normalexpanded{\ctxlatelua{_ptbs_['#1']={#2,"#3","#4"}}}}
% \def\dolazysavepositionwhd   #1#2#3#4#5#6#7{\normalexpanded{\ctxlatelua{_ptbs_['#1']={#2,"#3","#4","#5","#6","#7"}}}}
% \def\dolazysavepositionplus#1#2#3#4#5#6#7#8{\normalexpanded{\ctxlatelua{_ptbs_['#1']={#2,"#3","#4","#5","#6","#7","#8"}}}}
% \def\dosaveposition                #1#2#3#4{\normalexpanded{\ctxlua    {_ptbs_['#1']={#2,"#3","#4"}}}}
% \def\dosavepositionwhd       #1#2#3#4#5#6#7{\normalexpanded{\ctxlua    {_ptbs_['#1']={#2,"#3","#4","#5","#6","#7"}}}}
% \def\dosavepositionplus    #1#2#3#4#5#6#7#8{\normalexpanded{\ctxlua    {_ptbs_['#1']={#2,"#3","#4","#5","#6","#7","#8"}}}}
%
% \def\lastsavedpositionx {\the\dimexpr\pdflastxpos\scaledpoint\relax}
% \def\lastsavedpositiony {\the\dimexpr\pdflastypos\scaledpoint\relax}
% \let\savecurrentposition\pdfsavepos
%
% \def\dosetposition#1% will become commands.setposition
%   {\savecurrentposition
%    \normalexpanded{\ctxlatelua{_ptbs_['#1']={%
%      \noexpand\realfolio,"\noexpand\lastsavedpositionx","\noexpand\lastsavedpositiony"}}}}
%
% \def\dosetpositionwhd#1#2#3#4%
%   {\savecurrentposition
%    \normalexpanded{\ctxlatelua{_ptbs_['#1']={%
%      \noexpand\realfolio,"\noexpand\lastsavedpositionx","\noexpand\lastsavedpositiony","#2","#3","#4"}}}}
%
% \def\dosetpositionplus#1#2#3#4#5%
%   {\savecurrentposition
%    \normalexpanded{\ctxlatelua{_ptbs_['#1']={%
%      \noexpand\realfolio,"\noexpand\lastsavedpositionx","\noexpand\lastsavedpositiony","#2","#3","#4","#5"}}}}

\def\dosaveposition            #1#2#3#4{\normalexpanded{\ctxlua    {_plib_.setall("#1",\number#2,\number\dimexpr#3,\number\dimexpr#4)}}}
\def\dosavepositionwhd   #1#2#3#4#5#6#7{\normalexpanded{\ctxlua    {_plib_.setall("#1",\number#2,\number\dimexpr#3,\number\dimexpr#4,\number\dimexpr#5,\number\dimexpr#6,\number\dimexpr#7)}}}
\def\dosavepositionplus#1#2#3#4#5#6#7#8{\normalexpanded{\ctxlua    {_plib_.setall("#1",\number#2,\number\dimexpr#3,\number\dimexpr#4,\number\dimexpr#5,\number\dimexpr#6,\number\dimexpr#7,"#8")}}}

\def\dosetposition                   #1{\normalexpanded{\ctxlatelua{_plib_.setdim("#1")}}}
\def\dosetpositionwhd          #1#2#3#4{\normalexpanded{\ctxlatelua{_plib_.setdim("#1",\number\dimexpr#2,\number\dimexpr#3,\number\dimexpr#4)}}}
\def\dosetpositionplus       #1#2#3#4#5{\normalexpanded{\ctxlatelua{_plib_.setdim("#1",\number\dimexpr#2,\number\dimexpr#3,\number\dimexpr#4,"#5")}}}

% % %

\let\dosetpositionpapersize\gobbletwoarguments

\newbox\positionbox
\newif \ifpositioning

\def\POSprefix{POS::}

%D This is real tricky! The page anchor is applied to the
%D page box and therefore flushed first. So, when present, it
%D is applied to all positions except itself.

% 0 = don't relocate page origin  1 = relocate page origin once

\setnewconstant\positionanchormode\plusone

%D Sometimes we want to trick the position handler a bit:

% \def\replacepospxywhd#1#2#3#4#5#6#7%
%   {\ctxcommand{replacepospxywhd('#1',\number#2,"\the\dimexpr#3\relax","\the\dimexpr#4\relax","\the\dimexpr#5\relax","\the\dimexpr#6\relax","\the\dimexpr#7\relax")}}

\def\replacepospxywhd#1#2#3#4#5#6#7%
  {\ctxcommand{replacepospxywhd('#1',\number#2,\number\dimexpr#3,\number\dimexpr#4,\number\dimexpr#5,\number\dimexpr#6,\number\dimexpr#7)}}

%D The next switch can be used to communicate a special
%D situation. Positioning and associated actions can be
%D executed any time. However, in for instance backgrounds
%D they can be collected in a layer, for instance the text
%D layer (especially the hidden text layer). In the case of
%D floats, we run into problems, since the page information is
%D not applicable when the content floats indeed. In such
%D situations one can treat positions and graphics local.

\newif\iflocalpositioning % todo: conditional

%D Watch out: sometimes a pagebreak occurs inside a float
%D placement, so there we need to disable local mode.

\appendtoks
    \localpositioningtrue
\to \everyinsidefloat

\appendtoks
    \localpositioningfalse
\to \everypagebody

%D \macros
%D   {MPp, MPx, MPy, MPw, MPh, MPd,
%D    MPxy, MPll, MPlr, MPur, MPul, MPpos}
%D
%D Access to the positional information is provided by macros
%D with short names that are clearly meant for \METAPOST\ but
%D nowadays also used for other purposes.

\def\MPp  #1{\ctxcommand{MPp("#1")}}
\def\MPx  #1{\ctxcommand{MPx("#1")}}
\def\MPy  #1{\ctxcommand{MPy("#1")}}
\def\MPw  #1{\ctxcommand{MPw("#1")}}
\def\MPh  #1{\ctxcommand{MPh("#1")}}
\def\MPd  #1{\ctxcommand{MPd("#1")}}
\def\MPxy #1{\ctxcommand{MPxy("#1")}}
\def\MPll #1{\ctxcommand{MPll("#1")}}
\def\MPlr #1{\ctxcommand{MPlr("#1")}}
\def\MPur #1{\ctxcommand{MPur("#1")}}
\def\MPul #1{\ctxcommand{MPul("#1")}}
\def\MPpos#1{\ctxcommand{MPpos("#1")}}

%D \macros
%D  {MPplus, MPrest, MPv, MPvv}
%D
%D Since we will probably keep on extending, we provide a
%D general extension macro. The plus alternative takes an
%D extra argument, denoting what additional parameter to pick
%D up. So, the third extra is fetched with,
%D
%D \starttyping
%D \MPplus{identifier}{3}{default}
%D \stoptyping
%D
%D All extras (comma separated) are fetched with:
%D
%D \starttyping
%D \MPrest{identifier}
%D \stoptyping
%D
%D The extra parameters are not treated.

\def\MPplus#1#2#3{\ctxcommand{MPplus("#1",#2,"#3")}}  \let\MPv \MPplus
\def\MPrest  #1#2{\ctxcommand{MPrest("#1","#2")}}     \let\MPvv\MPrest

%D \macros
%D   {MPanchor}
%D
%D For readability we define a few synonyms:

\def\MPanchor{\MPpos}

%D There are two low level positioning macros. Both store the
%D position as well as execute an action associated with that
%D position.

\def\initializenextposition
  {\ifpositioning \else
     \global\positioningtrue
     \dosetpositionpapersize\printpaperwidth\printpaperheight
   \fi}

\def\setpositiononly#1%
  {\iftrialtypesetting
      % nothing
   \else
     \initializenextposition
     \def\currentposition{#1}%
     \dosetposition\currentposition
   \fi}

\def\setposition#1%
  {\iftrialtypesetting
      % nothing
   \else
     \initializenextposition
     \def\currentposition{#1}%
     \dosetposition\currentposition
     \traceposstring\llap\green{\currentposition>}%
     \dopositionaction\currentposition
   \fi}

\def\setpositiondata#1#2#3#4%
  {\iftrialtypesetting \else
     \initializenextposition
     \hbox
       {\def\currentposition{#1}%
        \dosetpositionwhd\currentposition
          {\the\dimexpr#2\relax}%
          {\the\dimexpr#3\relax}%
          {\the\dimexpr#4\relax}%
        \traceposstring\llap\green{\currentposition>}%
        \dopositionaction\currentposition
        \hss}%
   \fi}

\def\setpositionbox#1%
  {\dowithnextbox
     {\iftrialtypesetting
        \flushnextbox
      \else
        \initializenextposition
        \hbox to \nextboxwd
          {\edef\currentposition{#1}%
           \dosetpositionwhd\currentposition
             {\the\nextboxwd}%
             {\the\nextboxht}%
             {\the\nextboxdp}%
           \traceposstring\llap\green{\currentposition>}%
           \setbox\positionbox\flushnextbox
           \dopositionaction\currentposition
           \box\positionbox
           \hss}%
      \fi}}

\def\setpositiondataplus#1#2#3#4#5%
  {\iftrialtypesetting \else
     \initializenextposition
     \hbox % bug: to \nextboxwd
       {\edef\currentposition{#1}%
        \dosetpositionplus\currentposition
          {\the\dimexpr#2\relax}%
          {\the\dimexpr#3\relax}%
          {\the\dimexpr#4\relax}%
          {#5}%
        \traceposstring\rlap\magenta{<\currentposition}%
        \dopositionaction\currentposition
        \hss}%
   \fi}

\def\setpositionplus#1#2%
  {\dowithnextbox
     {\iftrialtypesetting
        \flushnextbox
      \else
        \initializenextposition
        \hbox to \nextboxwd
          {\edef\currentposition{#1}%
           \dosetpositionplus\currentposition
             {\the\nextboxwd}%
             {\the\nextboxht}%
             {\the\nextboxdp}%
             {#2}%
           \traceposstring\rlap\magenta{<\currentposition}%
           \setbox\positionbox\flushnextbox
           \dopositionaction\currentposition
           \box\positionbox
           \hss}%
      \fi}}

\let\currentposition\s!unknown

%D A few more low level macros take care of defining and
%D recalling actions. We could save this information in the
%D position containers themselves, this would save hash
%D entries, but at the cost of much more time consuming
%D expansion. Actions are saved globally!

\newtoks\everypositionaction

\let\POSactionprefix\POSprefix

\def\dosetpositionaction#1%
  {\setgvalue{\POSactionprefix#1::}}

%D The lists can become quite long (also because there can
%D be lots of parameters passed on) so we provide a hook
%D to clean up the list afterwards.

\let\cleanuppositionaction\gobbleoneargument

\def\doifpositionaction#1%
  {\ifcsname\POSactionprefix#1::\endcsname
     \@EA\firstofoneargument
   \else
     \@EA\gobbleoneargument
   \fi}

\def\doifpositionactionelse#1%
  {\ifcsname\POSactionprefix#1::\endcsname
     \@EA\firstoftwoarguments
   \else
     \@EA\secondoftwoarguments
   \fi}

%D We can copy a position with:
%D
%D \starttyping
%D \copyposition {to} {from}
%D \stoptyping
%D
%D Again, this is a global action.

\def\copyposition#1#2{\ctxcommand{copyposition('#1','#2')}}

%D The fact that handling positions is a two pass operation, is
%D one of the reasons why we need to be able to test for
%D existence, using:
%D
%D \starttyping
%D \doifpositionelse {identifier} {found action} {not found action}
%D \stoptyping

\def\doifpositionelse#1{\ctxcommand{doifpositionelse('#1')}}

%D We have now arrived at a few macros that would make sense as
%D support macros, but ended up in the core.

%D \macros
%D   {xypos}
%D
%D We have several macros available to save positions. Later
%D we will see applications.
%D
%D \starttabulate[|l|l||]
%D \NC \type {\xypos} \NC    \NC simple position with no dimensions \NC \NR
%D \NC \type {\hpos}  \NC    \NC position and characteristics of a \type {\hbox}                    \NC \NR
%D \NC \type {\vpos}  \NC    \NC position and characteristics of a \type {\vbox}                    \NC \NR
%D \NC \type {\bpos}  \NC b: \NC begin point in a line \NC \NR
%D \NC \type {\epos}  \NC e: \NC end point in a line \NC \NR
%D \NC \type {\fpos}  \NC f: \NC begin point in a paragraph \NC \NR
%D \NC \type {\tpos}  \NC t: \NC end point in a paragraph \NC \NR
%D \stoptabulate
%D
%D Each macro takes an identifier as argument, and the \type
%D {\hpos} and \type {\vpos} also expect box content.

% \def\xypos{\initializenextposition\dosetposition}

\let\xypos\setpositiononly

\def\hpos#1{\dontleavehmode\setpositionbox{#1}\hbox}
\def\vpos#1{\setpositionbox{#1}\vbox}

\def\bpos#1{\hpos{b:#1}{\strut}\ignorespaces}
\def\epos#1{\removelastspace\hpos{e:#1}{\strut}}

\def\fpos#1%
  {\setpositionplus{b:#1}{\number\parposcounter}\horizontalstrut
   \ignorespaces}

\def\tpos#1%
  {\removelastspace
   \setpositionplus{e:#1}{\number\parposcounter}\horizontalstrut}

\def\ffpos#1%
  {\setpositionplus{b:#1}{\number\parposcounter}\horizontalstrut\wpos{#1}%
   \ignorespaces}

\def\ttpos#1%
  {\removelastspace
   \setpositionplus{e:#1}{\number\parposcounter}\horizontalstrut}

\def\wpos#1%
  {\dontleavehmode\vadjust % may disappear if buried
     {\setbox0\hbox{\raise\strutdp\hbox{\rawwpos{#1}}}%
      \rlap{\smashedbox0}}}

\def\wwpos#1% \hsmashed{\llap{\rawwpos{#1}}}
  {\rlap
     {\setbox0\hbox{\rawwpos{#1}}%
      \smashedbox0}}

\def\rawwpos#1%
  {\hpos{w:#1}
     {\strut
      \hskip-\leftskip
      \hskip\hsize
      \hskip-\rightskip}}

% the next macro disables par positions (in inner boxes) and
% only registers the width

\def\setinnerparpositions
  {\let\fpos\ffpos
   \let\tpos\ttpos
   \let\wpos\wwpos}

% example of usage: (see for application "techniek")
%
% \appendtoks
%   \setinnerparpositions
% \to \everytabulate

%D When we want to calculate more complex backgrounds, we
%D need to know what the current indentation scheme is. At
%D the cost of many positions and memory, we can keep track
%D of them. This mechanism is activated automatically
%D based on information collected in the previous pass.

\newcount\parposcounter
\newif   \ifpositioningpar
\newif   \iftracepositions

% we can check for used entries, and if not, then not add one

\def\enableparpositions % global
  {\global\let\registerparoptions\doregisterparoptions
   \global\positioningtrue
   \global\positioningpartrue}

\def\disableparpositions % local
  {\positioningparfalse}

\let\registerparoptions\relax

\def\doregisterparoptions
  {\iftrialtypesetting \else
     \ifinpagebody \else \ifmmode \else \ifinformula \else
       \dodoregisterparoptions
     \fi \fi \fi
   \fi}

\def\dodoregisterparoptions
  {\global\advance\parposcounter\plusone
   \setpositiondataplus
     {p:\number\parposcounter}% identifier
     {\the\zeropoint}%
     {\the\strutht}%
     {\the\strutdp}%
     {\the\hsize,\the\dimexpr\leftskip\relax,\the\dimexpr\rightskip\relax,\the\hangindent,\the\hangafter,\the\parindent}%
  %\normalhbox{\registerparsymbol}%
   \iftracepositions\registerparsymbol\fi}

\def\traceposstring#1#2#3%
  {\iftracepositions
     \smashedhbox
       {#1{\infofont#2#3}%
        \scratchdimen.5\points
        \kern-2\scratchdimen
        \vrule\!!width4\scratchdimen\!!height\scratchdimen\!!depth\scratchdimen}%
   \fi}

\def\registerparsymbol
  {\iftracepositions
     \smashedhbox to \zeropoint
       {\hss
        \startcolor[blue]%
        \llap{\infofont\number\parposcounter}%
        \scratchdimen\onepoint
        \vrule
          \!!width 4\scratchdimen
          \!!height2\scratchdimen
          \!!depth 2\scratchdimen
        \stopcolor
        \hss}%
   \fi}

% \appendtoks \registerparoptions \to \everypar

%D Eperimental code, don't use this yet: (must be sped up anyway)

\def\@@noden{node:n:}
\def\@@nodeo{node:o:}
\def\@@nodep{node:p:}

\def\doifelsenodelocation#1%
  {\ifcsname\@@noden#1\endcsname
     \expandafter\firstoftwoarguments
   \else
     \expandafter\secondoftwoarguments
   \fi}

\def\nextnodelocation#1%
  {\ifcsname\@@noden#1\endcsname\pluscounter{\@@noden#1}\fi}

\def\newnodelocation#1%
  {\ifcsname\@@noden#1\endcsname
     \setcounter{\@@noden#1}\zerocount
     \letgvalue {\@@nodeo#1}\!!zerocount
   \fi}

\def\tagnodelocation#1%
  {\ifcsname\@@noden#1\endcsname\xypos{\@@nodep#1:\countervalue{\@@noden#1}}\fi}

\def\getnodelocationp#1{\MPp{\@@nodep#1:\countervalue{\@@noden#1}}}
\def\getnodelocationx#1{\MPx{\@@nodep#1:\countervalue{\@@noden#1}}}
\def\getnodelocationy#1{\MPy{\@@nodep#1:\countervalue{\@@noden#1}}}

\def\numnodelocationp#1#2{\MPp{\@@nodep#1:\number#2}}
\def\numnodelocationx#1#2{\MPx{\@@nodep#1:\number#2}}
\def\numnodelocationy#1#2{\MPy{\@@nodep#1:\number#2}}

\def\getnodelocationn#1{\countervalue{\@@noden#1}}
\def\getnodelocationo#1{\getvalue    {\@@nodeo#1}}

\setnewconstant\nodelocationmode\plusone

\def\analyzenodelocation#1%
  {\ifcsname\@@noden#1\endcsname
     \doanalyzenodelocation{#1}{\getnodelocationn{#1}}\zerocount
   \fi}

\def\doanalyzenodelocation#1#2#3% class n default
  {\begingroup
   \donefalse
   \ifcase\nodelocationmode
     % do nothing
   \else
     \edef\nodelocationselfn{#2}%
     \edef\nodelocationselfp{\numnodelocationp{#1}\nodelocationselfn}%
     \edef\nodelocationselfx{\numnodelocationx{#1}\nodelocationselfn}%
     \edef\nodelocationselfy{\numnodelocationy{#1}\nodelocationselfn}%
     \scratchcounter\plusone
     \doloop
       {\ifnum\recurselevel=\nodelocationselfn\relax
          \donetrue
        \else
          \edef\nodelocationotherp{\numnodelocationp{#1}\recurselevel}%
          \edef\nodelocationotherx{\numnodelocationx{#1}\recurselevel}%
          \edef\nodelocationothery{\numnodelocationy{#1}\recurselevel}%
          \ifcase\nodelocationmode
          \or
            % ok for single column
            \ifcase\nodelocationotherp\relax
              \exitloop
            \else\ifnum\nodelocationotherp<\nodelocationselfp\relax
              \donetrue \advance\scratchcounter\plusone
            \else\ifnum\nodelocationotherp>\nodelocationselfp\relax
              % skip
            \else\ifdim\nodelocationothery>\nodelocationselfy\relax
              \donetrue \advance\scratchcounter\plusone
            \else\ifdim\nodelocationothery<\nodelocationselfy\relax
              % skip
            \else\ifdim\nodelocationotherx<\nodelocationselfx\relax
              \donetrue \advance\scratchcounter\plusone
            \fi\fi\fi\fi\fi\fi
          \or
            % acceptable for double column
            \ifcase\nodelocationotherp\relax
              \exitloop
            \else\ifnum\nodelocationotherp<\nodelocationselfp\relax
              \donetrue \advance\scratchcounter\plusone
            \else\ifnum\nodelocationotherp>\nodelocationselfp\relax
              % skip
            \else\ifnum\recurselevel>\nodelocationselfn\relax
              \donetrue \exitloop
            \else
              \donetrue \advance\scratchcounter\plusone
            \fi\fi\fi\fi
        \else
          \exitloop
        \fi
        \fi}%
   \fi
   \ifdone \else
     \scratchcounter#3\relax
   \fi
   \setxvalue{\@@nodeo#1}{\the\scratchcounter}%
   \endgroup}

\unexpanded\def\shownodelocation#1%
  {\ifcsname\@@noden#1\endcsname
    \analyzenodelocation{#1}%
     (#1,%
      n:\getnodelocationn{#1},%
      p:\getnodelocationp{#1},%
      x:\getnodelocationx{#1},%
      y:\getnodelocationy{#1},%
      o:\getnodelocationo{#1})%
   \fi}

%D \macros
%D   {doifoverlappingelse}
%D
%D A first application of positional information, is to
%D determine if two boxes do overlap:
%D
%D \starttyping
%D \doifoverlappingelse{point a}{point b}
%D   {action when overlapping}
%D   {action when not overlapping}
%D \stoptyping

\def\doifoverlappingelse#1#2{\ctxcommand{doifoverlappingelse("#1","#2")}}

%D \macros
%D   {doifpositionsonsamepageelse,
%D    doifpositionsonthispageelse}
%D
%D Instead of letting the user handle fuzzy expansion, we
%D provide a simple test on positions being on the same page.
%D
%D \starttyping
%D \doifpositionsonsamepageelse{point a}{point b}
%D   {action when on same page}
%D   {action when not on same page}
%D \doifpositionsonthispageelse{point a}{point b}
%D   {action when on this page}
%D   {action when not on this page}
%D \stoptyping

\def\doifpositionsonsamepageelse#1{\ctxcommand{doifpositionsonsamepageelse("#1")}}
\def\doifpositionsonthispageelse#1{\ctxcommand{doifpositionsonthispageelse("#1")}}

%D Plugins:

\let\MPv     \MPplus
\let\MPvv    \MPrest
\let\MPanchor\MPpos

%D \macros
%D   {POSp, POSx, POSy, POSh, POSd, POSw}
%D
%D This is obsolete in \MKIV:

\let\POSp\MPp \let\POSx\MPx \let\POSy\MPy
\let\POSh\MPh \let\POSd\MPd \let\POSw\MPw

\protect \endinput