%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}

%D In \MKIV\ there was already a different housekeeping model
%D for positions quite early, but starting in 2012 more dramatic
%D changes started to happen, especially in relation to background
%D graphics. It will probably take some time to settle.

% 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

\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")}}}

\def\dosetposition            #1{\ctxcommand{posxy("#1")}}
\def\dosetpositionwhd   #1#2#3#4{\ctxcommand{poswhd("#1",\number\dimexpr#2,\number\dimexpr#3,\number\dimexpr#4)}}
\def\dosetpositionplus#1#2#3#4#5{\ctxcommand{posplus("#1",\number\dimexpr#2,\number\dimexpr#3,\number\dimexpr#4,"#5")}}
\def\dosetpositionbox       #1#2{\ctxcommand{poswhd("#1",\number\wd#2,\number\ht#2,\number\dp#2)}}
\def\dosetpositionstrut       #1{\ctxcommand{posstrut("#1")}}

\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 % not used

%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,\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
\newif\ifregionpositioning % 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
    \regionpositioningfalse
    \localpositioningfalse
\to \everybeforepagebody

%D \macros
%D   {MPp, MPx, MPy, MPw, MPh, MPd,
%D    MPxy, MPll, MPlr, MPur, MPul, MPpos,MPanchor}
%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")}}     \let\MPpage     \MPp
\def\MPr  #1{\ctxcommand{MPr("#1")}}     \let\MPregion   \MPr
\def\MPc  #1{\ctxcommand{MPc("#1")}}     \let\MPcolumn   \MPc
\def\MPn  #1{\ctxcommand{MPn("#1")}}     \let\MPparagraph\MPn
\def\MPx  #1{\ctxcommand{MPx("#1")}}
\def\MPy  #1{\ctxcommand{MPy("#1")}}
\def\MPw  #1{\ctxcommand{MPw("#1")}}     % first we need to replace \MPwidth etc
\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")}}    \let\MPanchor\MPpos  % overloaded locally when needed
\def\MPe  #1{\ctxcommand{MPe("#1")}}

\def\MPls #1{\ctxcommand{MPls("#1")}}     \let\MPleftskip\MPls % compatible feature
\def\MPrs #1{\ctxcommand{MPrs("#1")}}     \let\MPrightkip\MPrs % compatible feature

\def\MPpardata#1{\ctxcommand{MPpardata("#1")}}
\def\MPxywhd  #1{\ctxcommand{MPxywhd("#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 There are two low level positioning macros. Both store the
%D position as well as execute an action associated with that
%D position.

\let\dopositionaction\gobbleoneargument % implemented later

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

\unexpanded\def\setpositiononly
  {\iftrialtypesetting
     \expandafter\gobbleoneargument
   \else
     \expandafter\anch_positions_set_only_indeed
   \fi}

\def\anch_positions_set_only_indeed#1%
  {\anch_positions_initialize
   \edef\currentposition{#1}%
   \dosetposition\currentposition}

\unexpanded\def\setposition
  {\iftrialtypesetting
     \expandafter\gobbleoneargument
   \else
     \expandafter\anch_positions_set_indeed
   \fi}

\def\anch_positions_set_indeed#1%
  {\anch_positions_initialize
   \edef\currentposition{#1}%
   \dosetposition\currentposition
   \traceposstring\llap\green{\currentposition>}%
   \dopositionaction\currentposition}

\unexpanded\def\setpositiondata
  {\iftrialtypesetting
     \expandafter\gobblefourarguments
   \else
     \expandafter\anch_positions_set_data_indeed
   \fi}

\def\anch_positions_set_data_indeed#1#2#3#4%
  {\anch_positions_initialize
   \hbox
     {\edef\currentposition{#1}%
      \dosetpositionwhd\currentposition{#2}{#3}{#4}% already \the\dimexpr
      \traceposstring\llap\green{\currentposition>}%
      \dopositionaction\currentposition
      \hss}}

\unexpanded\def\setpositionbox
  {\iftrialtypesetting
     \expandafter\anch_positions_set_box_nop
   \else
     \expandafter\anch_positions_set_box_yes
   \fi}

\def\anch_positions_set_box_nop#1%
  {\dowithnextboxcs\flushnextbox}

\def\anch_positions_set_box_yes#1%
  {\dowithnextbox{\anch_positions_set_box_finish{#1}}}

\def\anch_positions_set_box_finish#1%
  {\anch_positions_initialize
   \hbox to \wd\nextbox
     {\edef\currentposition{#1}%
      \dosetpositionbox\currentposition\nextbox
      \traceposstring\llap\green{\currentposition>}%
      \setbox\positionbox\box\nextbox
      \dopositionaction\currentposition
      \box\positionbox
      \hss}}

\unexpanded\def\setpositionstrut
  {\iftrialtypesetting
     \expandafter\anch_positions_set_strut_nop
   \else
     \expandafter\anch_positions_set_strut_yes
   \fi}

\def\anch_positions_set_strut_nop#1%
  {\strut}

\def\anch_positions_set_strut_yes#1%
  {\anch_positions_initialize
   \hbox to \zeropoint
     {\edef\currentposition{#1}%
      \dosetpositionstrut\currentposition
      \traceposstring\llap\green{\currentposition>}%
      \dopositionaction\currentposition
      \strut
      \hss}}

\def\setpositiondataplus
  {\iftrialtypesetting
     \expandafter\gobblefivearguments
   \else
     \expandafter\anch_positions_set_plus_indeed
   \fi}

\def\anch_positions_set_plus_indeed#1#2#3#4#5%
  {\anch_positions_initialize
   \hbox % just package
     {\edef\currentposition{#1}%
      \dosetpositionplus\currentposition{#2}{#3}{#4}{#5}% already \the\dimexpr
      \traceposstring\rlap\magenta{<\currentposition}%
      \dopositionaction\currentposition
      \hss}}

\def\setpositionplus
  {\iftrialtypesetting
     \expandafter\anch_positions_set_plus_nop
   \else
     \expandafter\anch_positions_set_plus_yes
   \fi}

\def\anch_positions_set_plus_nop#1#2%
  {\dowithnextboxcs\flushnextbox}

\def\anch_positions_set_plus_yes#1#2%
  {\dowithnextbox{\anch_positions_set_plus_yes_finish{#1}{#2}}}

\def\anch_positions_set_plus_yes_finish#1#2%
  {\anch_positions_initialize
   \hbox to \nextboxwd
     {\edef\currentposition{#1}%
      \dosetpositionplus\currentposition{\wd\nextbox}{\ht\nextbox}{\dp\nextbox}{#2}%
      \traceposstring\rlap\magenta{<\currentposition}%
      \setbox\positionbox\flushnextbox
      \dopositionaction\currentposition
      \box\positionbox
      \hss}}

\let\currentposition\s!unknown

%D A few special ones .. will be cleaned up

\def\pageanchor  {page:\the\realpageno} % for the moment only one pagesize
\def\textanchor  {text:\the\realpageno}
\def\regionanchor{region:0}

\newcount\c_anch_column % will be delegated to lua
\newcount\c_anch_text   % will be delegated to lua

\unexpanded\def\anch_mark_column_box#1%
  {\global\advance\c_anch_column\plusone
   \ctxcommand{markregionbox(\number#1,"columnarea:\the\c_anch_column")}} % extra height

\unexpanded\def\anch_mark_region_box
  {\iftrialtypesetting
     \singleexpandafter\gobbleoneargument
   \else\ifpositioning
     \doubleexpandafter\gobbleoneargument
   \else
     \doubleexpandafter\anch_mark_region_box_indeed
   \fi\fi}

\unexpanded\def\anch_mark_region_box#1%
  {\ctxcommand{markregionbox(\number#1)}}

\unexpanded\def\anch_mark_flow_box#1% will be extended / renamed
  {\hbox\bgroup
   \global\advance\c_anch_text\plusone
   \ctxcommand{markregionbox(\number#1,"textarea:\the\c_anch_text")}%
   \box#1%
   \egroup}

\unexpanded\def\anch_make_page_box#1% maybe like text
  {\ctxcommand{markregionbox(\number#1,"\pageanchor")}} % needs an hbox

\unexpanded\def\anch_mark_text_box#1%
  {\ctxcommand{markregionbox(\number#1,"\textanchor")}} % needs an hbox

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

\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')}}
\def\doifposition    #1{\ctxcommand{doifposition('#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{\anch_positions_initialize\dosetposition}

\let\xypos\setpositiononly

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

\unexpanded\def\bpos #1{\dontleavehmode      \setpositionstrut{b:#1}\ignorespaces}
\unexpanded\def\epos #1{\removeunwantedspaces\setpositionstrut{e:#1}}

%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

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

\unexpanded\def\disableparpositions % local
  {\positioningparfalse}

\let\registerparoptions\relax

\unexpanded\def\doregisterparoptions
  {\iftrialtypesetting \else
     \ifinpagebody \else \ifmmode \else \ifinformula \else
       \anch_positions_register_par_options
     \fi \fi \fi
   \fi}

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

\def\anch_positions_register_par_options
  {\dontleavehmode\ctxcommand{parpos()}%
   \iftracepositions\registerparsymbol\fi}

\unexpanded\def\traceposstring#1#2#3%
  {\iftracepositions
     \smashedhbox
       {#1{\infofont#2#3}%
        \kern-\onepoint
        \vrule\!!width2\onepoint\!!height\halfapoint\!!depth\halfapoint}%
   \fi}

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

% \appendtoks \registerparoptions \to \everypar

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

\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
     \anch_positions_node_location_analyze{#1}{\getnodelocationn{#1}}\zerocount
   \fi}

\def\anch_positions_node_location_analyze#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
            % \exitloop
          \or
            % ok for single column
            \anch_positions_node_location_analyze_one
          \or
            % acceptable for double column
            \anch_positions_node_location_analyze_two
          \else
            \exitloop
          \fi
        \fi}%
   \fi
   \ifdone \else
     \scratchcounter#3\relax
   \fi
   \setxvalue{\@@nodeo#1}{\the\scratchcounter}%
   \endgroup}

\def\anch_positions_node_location_analyze_one
  {\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}

\def\anch_positions_node_location_analyze_two
  {\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}

\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 \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