beta 2013.01.07 23:25

48 files changed, 1098 insertions, 122 deletions

diff --git a/tex/context/base/buff-ini.mkiv b/tex/context/base/buff-ini.mkiv
index 8160fa613..7616a1dee 100644
--- a/tex/context/base/buff-ini.mkiv
+++ b/tex/context/base/buff-ini.mkiv
@@ -34,9 +34,9 @@
 \setuvalue{\e!start\v!buffer}%
   {\begingroup % (3)
    \obeylines
-   \dosingleempty\buff_start}
+   \dodoubleempty\buff_start}
 
-\def\buff_start[#1]%
+\def\buff_start[#1][#2]%
   {\buff_start_indeed{}{#1}{\e!start\v!buffer}{\e!stop\v!buffer}}
 
 \def\buff_start_indeed#1#2#3#4% \donothing needed !
@@ -182,7 +182,7 @@
   {\begingroup
    \doifassignmentelse{#1}
      {\setupcurrentsavebuffer[#1]}%
-     {\setupcurrentsavebuffer[\c!list=#1,\c!file=#2]}%
+     {\setupcurrentsavebuffer[\c!list={#1},\c!file=#2]}%
    \ctxcommand{savebuffer("\directsavebufferparameter\c!list","\directsavebufferparameter\c!file","\directsavebufferparameter\c!prefix")}%
    \endgroup}
 
diff --git a/tex/context/base/char-def.lua b/tex/context/base/char-def.lua
index 29a325697..60e445ea9 100644
--- a/tex/context/base/char-def.lua
+++ b/tex/context/base/char-def.lua
@@ -3192,8 +3192,6 @@ characters.data={
   description="LATIN SMALL LETTER H WITH STROKE",
   direction="l",
   linebreak="al",
-  mathclass="ord",
-  mathname="hbar",
   shcode=0x0068,
   uccode=0x0126,
   unicodeslot=0x0127,
@@ -58119,8 +58117,16 @@ characters.data={
   description="PLANCK CONSTANT OVER TWO PI",
   direction="l",
   linebreak="al",
-  mathclass="variable",
-  mathname="hslash",
+  mathspec={
+   {
+     class="variable",
+     name="hslash",
+   },
+   {
+     class="ord",
+     name="hbar",
+   },
+  },
   specials={ "font", 0x0127 },
   unicodeslot=0x210F,
  },
@@ -187663,4 +187669,4 @@ characters.data={
   linebreak="cm",
   unicodeslot=0xE01EF,
  },
-}
\ No newline at end of file
+}
diff --git a/tex/context/base/chem-str.mkiv b/tex/context/base/chem-str.mkiv
index cb840ed80..efd1e6547 100644
--- a/tex/context/base/chem-str.mkiv
+++ b/tex/context/base/chem-str.mkiv
@@ -593,23 +593,6 @@
 \unexpanded\def\formulachemical
   {\relax\dotriplegroupempty\chem_formula}
 
-% \def\chem_formula#1#2#3% we could do hboxes and measure
-%   {\ifcsname\??chemicalsymbol\detokenize{#1}\endcsname
-%      \t_chem_mid\expandafter{\the\t_chem_mid\chem_formula_mid{#1}{#2}{#3}}%
-%    \else
-%      \ifthirdargument
-%        \doifelsenothing{#2}\chem_formula_top_nop{\chem_formula_top_yes{#2}}%
-%        \doifelsenothing{#3}\chem_formula_bot_nop{\chem_formula_bot_yes{#3}}%
-%      \else\ifsecondargument
-%        \chem_formula_top_nop
-%        \doifelsenothing{#2}\chem_formula_bot_nop{\chem_formula_bot_yes{#2}}%
-%      \else
-%        \chem_formula_top_nop
-%        \chem_formula_bot_nop
-%      \fi\fi
-%      \t_chem_mid\expandafter{\the\t_chem_mid\molecule{#1}\aligntab}%
-%    \fi}
-
 \def\chem_formula#1#2#3% we could do hboxes and measure
   {\ifthirdargument
      \doifelsenothing{#2}\chem_formula_top_nop{\chem_formula_top_yes{#2}}%
diff --git a/tex/context/base/cont-new.mkii b/tex/context/base/cont-new.mkii
index 1c7abf47e..945da783e 100644
--- a/tex/context/base/cont-new.mkii
+++ b/tex/context/base/cont-new.mkii
@@ -11,7 +11,7 @@
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
-\newcontextversion{2013.01.02 18:19}
+\newcontextversion{2013.01.07 23:25}
 
 %D This file is loaded at runtime, thereby providing an
 %D excellent place for hacks, patches, extensions and new
diff --git a/tex/context/base/cont-new.mkiv b/tex/context/base/cont-new.mkiv
index 612d225e2..73f67a61e 100644
--- a/tex/context/base/cont-new.mkiv
+++ b/tex/context/base/cont-new.mkiv
@@ -11,7 +11,7 @@
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
-\newcontextversion{2013.01.02 18:19}
+\newcontextversion{2013.01.07 23:25}
 
 %D This file is loaded at runtime, thereby providing an excellent place for
 %D hacks, patches, extensions and new features.
diff --git a/tex/context/base/context-version.pdf b/tex/context/base/context-version.pdf
index db3542344..42db0bec5 100644
--- a/tex/context/base/context-version.pdf
+++ b/tex/context/base/context-version.pdf
diff --git a/tex/context/base/context-version.png b/tex/context/base/context-version.png
index db1256efe..c7091dca5 100644
--- a/tex/context/base/context-version.png
+++ b/tex/context/base/context-version.png
diff --git a/tex/context/base/context.mkii b/tex/context/base/context.mkii
index f052759f8..3cd9c6955 100644
--- a/tex/context/base/context.mkii
+++ b/tex/context/base/context.mkii
@@ -20,7 +20,7 @@
 %D your styles an modules.
 
 \edef\contextformat {\jobname}
-\edef\contextversion{2013.01.02 18:19}
+\edef\contextversion{2013.01.07 23:25}
 
 %D For those who want to use this:
 
diff --git a/tex/context/base/context.mkiv b/tex/context/base/context.mkiv
index 8b3bed1c1..8948430cd 100644
--- a/tex/context/base/context.mkiv
+++ b/tex/context/base/context.mkiv
@@ -25,7 +25,7 @@
 %D up and the dependencies are more consistent.
 
 \edef\contextformat {\jobname}
-\edef\contextversion{2013.01.02 18:19}
+\edef\contextversion{2013.01.07 23:25}
 
 %D For those who want to use this:
 
diff --git a/tex/context/base/font-mis.lua b/tex/context/base/font-mis.lua
index c0ee7dec4..c103d57d5 100644
--- a/tex/context/base/font-mis.lua
+++ b/tex/context/base/font-mis.lua
@@ -22,7 +22,7 @@ local handlers = fonts.handlers
 handlers.otf   = handlers.otf or { }
 local otf      = handlers.otf
 
-otf.version    = otf.version or 2.737
+otf.version    = otf.version or 2.738
 otf.cache      = otf.cache   or containers.define("fonts", "otf", otf.version, true)
 
 function otf.loadcached(filename,format,sub)
diff --git a/tex/context/base/font-otf.lua b/tex/context/base/font-otf.lua
index 8e9930a54..4d0828209 100644
--- a/tex/context/base/font-otf.lua
+++ b/tex/context/base/font-otf.lua
@@ -47,7 +47,7 @@ local otf                = fonts.handlers.otf
 
 otf.glists               = { "gsub", "gpos" }
 
-otf.version              = 2.737 -- beware: also sync font-mis.lua
+otf.version              = 2.738 -- beware: also sync font-mis.lua
 otf.cache                = containers.define("fonts", "otf", otf.version, true)
 
 local fontdata           = fonts.hashes.identifiers
diff --git a/tex/context/base/m-chart.lua b/tex/context/base/m-chart.lua
index a00f246a9..a5201fc98 100644
--- a/tex/context/base/m-chart.lua
+++ b/tex/context/base/m-chart.lua
@@ -36,10 +36,10 @@ local defaults = {
         name            = "",
         option          = "",
         backgroundcolor = "",
-        width           = 100*65436,
-        height          = 50*65436,
-        dx              = 30*65436,
-        dy              = 30*65436,
+        width           = 100*65536,
+        height          = 50*65536,
+        dx              = 30*65536,
+        dy              = 30*65536,
         offset          = 0,
         bodyfont        = "",
         dot             = "",
@@ -47,25 +47,25 @@ local defaults = {
         vcompact        = variables_no,
         autofocus       = "",
         focus           = "",
-        labeloffset     = 5*65436,
-        commentoffset   = 5*65436,
+        labeloffset     = 5*65536,
+        commentoffset   = 5*65536,
         exitoffset      = 0,
 
     },
     shape = { -- FLOS
-        rulethickness   = 65436,
+        rulethickness   = 65536,
         default         = "",
         framecolor      = "darkblue",
         backgroundcolor = "lightgray",
     },
     focus = { -- FLOF
-        rulethickness   = 65436,
+        rulethickness   = 65536,
         framecolor      = "darkred",
         backgroundcolor = "gray",
     },
     line = { -- FLOL
-        rulethickness   = 65436,
-        radius          = 10*65436,
+        rulethickness   = 65536,
+        radius          = 10*65536,
         color           = "darkgreen",
         corner          = "",
         dash            = "",
diff --git a/tex/context/base/math-act.lua b/tex/context/base/math-act.lua
index 71b9353d5..eaeb15656 100644
--- a/tex/context/base/math-act.lua
+++ b/tex/context/base/math-act.lua
@@ -14,6 +14,8 @@ local report_math    = logs.reporter("mathematics","initializing")
 local context        = context
 local commands       = commands
 local mathematics    = mathematics
+local texdimen       = tex.dimen
+local abs            = math.abs
 
 local sequencers     = utilities.sequencers
 local appendgroup    = sequencers.appendgroup
@@ -216,45 +218,101 @@ local fontcharacters     = fonts.hashes.characters
 local extensibles        = utilities.storage.allocate()
 fonts.hashes.extensibles = extensibles
 
+local chardata           = characters.data
+local extensibles        = mathematics.extensibles
+
+-- we use numbers at the tex end (otherwise we could stick to chars)
+
+local e_left       = extensibles.left
+local e_right      = extensibles.right
+local e_horizontal = extensibles.horizontal
+local e_vertical   = extensibles.vertical
+local e_mixed      = extensibles.mixed
+local e_unknown    = extensibles.unknown
+
+local unknown      = { e_unknown, false, false }
+
 local function extensiblecode(font,unicode)
     local characters = fontcharacters[font]
-    local chardata = characters[unicode]
-    if not chardata then
-        return 0
+    local character = characters[unicode]
+    if not character then
+        return unknown
     end
-    local next = chardata.next
+    local code = unicode
+    local next = character.next
     while next do
-        chardata = characters[next]
-        next = chardata.next
+        code = next
+        character = characters[next]
+        next = character.next
     end
-    if chardata.horiz_variants then
-        if chardata.vert_variants then
-            return 4
+    local char = chardata[unicode]
+    local matharrow = char and char.matharrow
+    if character.horiz_variants then
+        if character.vert_variants then
+            return { e_mixed, code, character }
         else
-            return 1
+            local e = matharrow and extensibles[matharrow]
+            return e and { e, code, character } or unknown
         end
-    elseif chardata.vert_variants then
-        return 2
+    elseif character.vert_variants then
+        local e =  matharrow and extensibles[matharrow]
+        return e and { e, code, character } or unknown
     else
-        return 0
+        return unknown
     end
 end
 
 setmetatableindex(extensibles,function(extensibles,font)
     local codes = { }
     setmetatableindex(codes, function(codes,unicode)
-        local code = extensiblecode(font,unicode)
-        codes[unicode] = code
-        return code
+        local status = extensiblecode(font,unicode)
+        codes[unicode] = status
+        return status
     end)
     extensibles[font] = codes
     return codes
 end)
 
 function mathematics.extensiblecode(family,unicode)
-    return extensibles[family_font(family or 0)][unicode]
+    return extensibles[family_font(family or 0)][unicode][1]
 end
 
 function commands.extensiblecode(family,unicode)
-    context(extensibles[family_font(family or 0)][unicode])
+    context(extensibles[family_font(family or 0)][unicode][1])
+end
+
+-- left       : [head] ...
+-- right      : ... [head]
+-- horizontal : [head] ... [head]
+--
+-- abs(right["start"] - right["end"]) | right.advance | characters[right.glyph].width
+
+function commands.horizontalcode(family,unicode)
+    local font = family_font(family or 0)
+    local data = extensibles[font][unicode]
+    local kind = data[1]
+    if kind == e_left then
+        local charlist = data[3].horiz_variants
+        local characters = fontcharacters[font]
+        local left = charlist[1]
+        texdimen.scratchleftoffset  = abs((left["start"] or 0) - (left["end"] or 0))
+        texdimen.scratchrightoffset = 0
+    elseif kind == e_right then
+        local charlist = data[3].horiz_variants
+        local characters = fontcharacters[font]
+        local right = charlist[#charlist]
+        texdimen.scratchleftoffset  = 0
+        texdimen.scratchrightoffset = abs((right["start"] or 0) - (right["end"] or 0))
+     elseif kind == e_horizontal then
+        local charlist = data[3].horiz_variants
+        local characters = fontcharacters[font]
+        local left = charlist[1]
+        local right = charlist[#charlist]
+        texdimen.scratchleftoffset  = abs((left["start"] or 0) - (left["end"] or 0))
+        texdimen.scratchrightoffset = abs((right["start"] or 0) - (right["end"] or 0))
+    else
+        texdimen.scratchleftoffset  = 0
+        texdimen.scratchrightoffset = 0
+    end
+    context(kind)
 end
diff --git a/tex/context/base/math-arr.mkiv b/tex/context/base/math-arr.mkiv
index 179e4de8a..e0ef6095e 100644
--- a/tex/context/base/math-arr.mkiv
+++ b/tex/context/base/math-arr.mkiv
@@ -215,13 +215,13 @@
   {\setuvalue{#1}{\math_arrows_do[#2][#3]}}
 
 \unexpanded\def\math_arrows_do
-  {\dotripleempty\math_arrows_handle}
+  {\doquadrupleempty\math_arrows_handle}
 
-\def\math_arrows_handle[#1][#2][#3]% #3 == optional arg .. \empty can be just 'empty'
+\def\math_arrows_handle[#1][#2][#3][#4]% #3 == optional arg .. \empty can be just 'empty' [#4] gobbles spaces
   {\def\math_arrows_handle_indeed{\math_arrows_handle_finalize[#1,\empty,\empty][#2,\empty,\empty][#3]}% {##1}{##2}
    \dodoublegroupempty\math_arrows_handle_indeed}
 
-\def\math_arrows_handle_finalize[#1,#2,#3][#4,#5,#6][#7]#8#9% [3] is the optional arg
+\def\math_arrows_handle_finalize[#1,#2,#3][#4,#5,#6][#7]#8#9% [#7] is the optional arg
   {\edef\!!stringa{#2}%
    \ifx\!!stringa\empty
      \ifsecondargument
diff --git a/tex/context/base/math-fbk.lua b/tex/context/base/math-fbk.lua
index 826f50f7c..565bead1d 100644
--- a/tex/context/base/math-fbk.lua
+++ b/tex/context/base/math-fbk.lua
@@ -267,7 +267,7 @@ virtualcharacters[0xFE350] = function(data)
 end
 
 virtualcharacters[0xFE351] = function(data)
- -- return combined(data,0x2212,0x2212) -- relbar, relbar
+ -- return combined(data,0x2212,0x2212) -- relbar, relbar  (isn't that just equal)
     local char = data.characters[0x2212]
     if char then
         local size = data.size/2
diff --git a/tex/context/base/math-ini.lua b/tex/context/base/math-ini.lua
index af9a8495e..22a079337 100644
--- a/tex/context/base/math-ini.lua
+++ b/tex/context/base/math-ini.lua
@@ -85,17 +85,20 @@ local codes = allocate {
     variable       = 7, [7] = "variable",
 }
 
-local arrowtypes = allocate {
-    l = "left",
-    r = "right",
-    u = "up",
-    d = "down",
-    h = "horizontal", -- double : lr or rl
-    v = "vertical",   -- double : ud or du
-    m = "mixed",
+local extensibles = allocate {
+           unknown    = 0,
+    l = 1, left       = 1,
+    r = 2, right      = 2,
+    h = 3, horizontal = 3,-- lr or rl
+    u = 5, up         = 4,
+    d = 5, down       = 5,
+    v = 6, vertical   = 6,-- ud or du
+    m = 7, mixed      = 7,
 }
 
-mathematics.arrowtypes      = arrowtypes
+table.setmetatableindex(extensibles,function(t,k) t[k] = 0 return 0 end)
+
+mathematics.extensibles     = extensibles
 mathematics.classes         = classes
 mathematics.codes           = codes
 -----------.accents         = codes
diff --git a/tex/context/base/math-ini.mkiv b/tex/context/base/math-ini.mkiv
index a1f747a79..8c5b59356 100644
--- a/tex/context/base/math-ini.mkiv
+++ b/tex/context/base/math-ini.mkiv
@@ -1312,7 +1312,10 @@
 % \def\mathextensiblecode#1#2%
 %   {\cldcontext{mathematics.extensiblecode(\number#1,\number#2)}}
 
-\def\mathextensiblecode#1#2% should be a primitive
+\def\mathextensiblecode#1#2%
   {\ctxcommand{extensiblecode(\number#1,\number#2)}}
 
+\def\mathhorizontalcode#1#2%
+  {\ctxcommand{horizontalcode(\number#1,\number#2)}}
+
 \protect \endinput
diff --git a/tex/context/base/math-stc.mkvi b/tex/context/base/math-stc.mkvi
new file mode 100644
index 000000000..4760c4b3c
--- /dev/null
+++ b/tex/context/base/math-stc.mkvi
@@ -0,0 +1,766 @@
+%D \module
+%D   [       file=math-stc,
+%D        version=2012.12.29,
+%D          title=\CONTEXT\ Math Macros,
+%D       subtitle=Stackers,
+%D        comment=This replaces math-arr and friends,
+%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 Math Macros / Stackers}
+
+\unprotect
+
+%D At some point the \MKII\ arrow mechanism has been converted to \MKIV, but we kept
+%D most of the logic. We now have a more generic variant dealing with extensibles.
+%D There are a few demands than we need to meet:
+%D
+%D \startitemize
+%D \startitem The width of the extensible need to adapt itself automatically. \stopitem
+%D \startitem We need to be able to control horizontal and vertical offsets. \stopitem
+%D \startitem We best have a math as well as a text variant (which is handy for chemistry). \stopitem
+%D \startitem For historic reasons we need to deal with optional arguments in a special (reverse) way. \stopitem
+%D \startitem We need alternatives for extensibles on top, in the middle and at the bottom. \stopitem
+%D \stopitemize
+%D
+%D After I had experimented a bit with virtual characters for two headed arrows I
+%D discussed the issue with the Gyre folks and we came to the conclusion that it
+%D made sense to have real extensibles instead of constructing them out of snippets.
+%D After all, \OPENTYPE\ math provides for it. So, in December 2013 beta versions of
+%D Latin Modern and Gyre fonts came available that had these! Because we still want
+%D to support the traditional Latin Modern Virtual math font those were extended
+%D with a couple of virtual extensibles as well.
+%D
+%D {\em For the moment we still have some mess here: we can deal with known dimensions, but
+%D fillers (like \type {\rightarrowfil} don't work with \OPENTYPE\ extensibles yet
+%D because there is no way to let them stretch like leaders. At some point \LUATEX\
+%D might provide a auto||fit||to||encapsulated||box and if not I will cook up a \LUA\
+%D based variant.}
+%D
+%D We could mess with something like \type {$mid\limits^{top}_{bottom}$} but we like
+%D a bit more control. At some point we need to add some hacks to get exports
+%D working well.
+%D
+%D In the end we have a more flexible mechanism which also handles text variants.
+
+% possible improvements:
+%
+% - we could skip the left/right offsets when offset=normal, this saves some access time
+%   at the lua end and some checking: use \mathhorizontalcode or \mathextensiblecode
+%   but in practice arrows etc are not used that often
+
+\installcorenamespace {mathextensiblefallbacks}
+
+\def\math_stackers_fallback
+  {\hbox to \scratchwidth{\csname\??mathextensiblefallbacks\ifcsname\??mathextensiblefallbacks\number\scratchunicode\endcsname\number\scratchunicode\fi\endcsname}}
+ %{\csname\??mathextensiblefallbacks\ifcsname\??mathextensiblefallbacks\number\scratchunicode\endcsname\number\scratchunicode\fi\endcsname }
+
+\def\math_stackers_regular
+  {\mathstylehbox{\Umathaccent\fam\zerocount\scratchunicode{\hskip\scratchwidth}}}
+
+\def\math_stackers_stretch % we don't have that one yet
+  {\mathstylehbox{\Umathaccent\fam\zerocount\scratchunicode{\hskip\hsize}}}
+
+\setvalue{\??mathextensiblefallbacks}{\hbox{\vrule\!!width\scratchwidth\!!height.1\exheight\!!depth\zeropoint}}
+
+\def\math_stackers_with_fallback#codepoint%
+  {\begingroup
+   \scratchunicode#codepoint\relax
+   \ifcase\mathextensiblecode\fam\scratchunicode\relax
+     \math_stackers_fallback
+   \else
+     \math_stackers_stretch
+   \fi
+   \endgroup}
+
+%D We don't really need this because we can assume that fonts have the right
+%D extensibles. If needed I will make a general virtual extender for \OPENTYPE\
+%D fonts.
+%D
+%D Because we have quite some control over positioning, we have somewhat extensive
+%D tracing built in.
+
+\let\math_stackers_top   \relax
+\let\math_stackers_middle\relax
+\let\math_stackers_bottom\relax
+\let\math_stackers_skip  \hskip
+
+\installtextracker
+  {math.stackers.texts}
+  {\let\math_stackers_top   \filledhboxb
+   \let\math_stackers_middle\filledhboxr
+   \let\math_stackers_bottom\filledhboxg
+   \let\math_stackers_skip  \math_stackers_skip_indeed}
+  {\let\math_stackers_top   \relax
+   \let\math_stackers_middle\relax
+   \let\math_stackers_bottom\relax
+   \let\math_stackers_skip  \hskip}
+
+\def\math_stackers_skip_indeed#amount%
+  {\filledhboxk{\unsetteststrut\strut\hskip#amount}} % \dontshowstruts
+
+%D We define a full featured command handler.
+
+\installcorenamespace {mathstackers}
+
+\installcommandhandler \??mathstackers {mathstackers} \??mathstackers
+
+\setupmathstackers
+  [%c!alternative=\v!text,    % text | mathematics
+   \c!left=,
+   \c!right=,
+   \c!voffset=.25\exheight,
+   \c!hoffset=.5\emwidth,
+   \c!minheight=\exheight,
+   \c!mindepth=\zeropoint,
+   \c!minwidth=\emwidth,
+   \c!order=\v!normal,
+   \c!topcommand=,
+   \c!middlecommand=,
+   \c!bottomcommand=,
+   \c!offset=\v!normal,       % normal | min | max
+   \c!location=\v!top]        % none | normal | small | medium | big
+
+%D We assume that the middle characters (that can be an extensible) to sit on
+%D top of the baseline by default.
+
+\installcorenamespace {mathstackerslocation}
+
+\letvalue{\??mathstackerslocation\v!top    }\plusone   % on top of baseline
+\letvalue{\??mathstackerslocation\v!high   }\plustwo   % 25 % down
+\letvalue{\??mathstackerslocation\v!middle }\plusthree % centered
+\letvalue{\??mathstackerslocation\v!low    }\plusfour  % 75 % down
+\letvalue{\??mathstackerslocation\v!bottom }\plusfive  % below baseline
+\letvalue{\??mathstackerslocation          }\zerocount
+
+%D First we implement the helper that deals with an extensible in the middle and
+%D top and|/|or bottom texts:
+
+\let\m_math_stackers_text_top   \empty
+\let\m_math_stackers_text_bottom\empty
+\let\m_math_stackers_text_middle\empty
+
+\def\math_stackers_flushtext#command#text%
+  {\ifdim\scratchleftoffset >\zeropoint\math_stackers_skip\scratchleftoffset \fi
+   \strut\mathstackersparameter#command#text%
+   \ifdim\scratchrightoffset>\zeropoint\math_stackers_skip\scratchrightoffset\fi}
+
+\def\math_stackers_toptext   {\math_stackers_flushtext\c!topcommand   \m_math_stackers_text_top   }
+\def\math_stackers_bottomtext{\math_stackers_flushtext\c!bottomcommand\m_math_stackers_text_bottom}
+\def\math_stackers_middletext{\math_stackers_flushtext\c!middlecommand\m_math_stackers_text_middle}
+
+\def\math_stackers_content
+  {\ifcase\scratchcounter
+     \math_stackers_fallback
+   \or % left
+     \math_stackers_regular
+   \or % right
+     \math_stackers_regular
+   \or % horizontal
+     \math_stackers_regular
+   \else
+     \math_stackers_fallback
+   \fi}
+
+\def\math_stackers_check_unicode#codepoint%
+  {\scratchunicode#codepoint\relax
+   \scratchhoffset\mathstackersparameter\c!hoffset\relax
+   \scratchvoffset\mathstackersparameter\c!voffset\relax
+   \scratchcounter\mathhorizontalcode\fam\scratchunicode\relax % also sets \leftscratchoffset and \rightscratchoffset
+   \ifx\p_offset\v!max
+     % heads/tails + hoffset
+   \else\ifx\p_offset\v!min
+     % heads/tails - hoffset
+     \advance\scratchleftoffset -\scratchhoffset
+     \advance\scratchrightoffset-\scratchhoffset
+   \else % \v!normal
+     % hoffset
+     \scratchleftoffset \zeropoint
+     \scratchrightoffset\zeropoint
+   \fi\fi
+   \ifdim\scratchleftoffset <\zeropoint
+     \scratchleftoffset \zeropoint
+   \fi
+   \ifdim\scratchrightoffset<\zeropoint
+     \scratchrightoffset\zeropoint
+   \fi}
+
+\def\math_stackers_normalize_three
+  {\scratchheight\ht\scratchboxthree
+   \scratchdepth \dp\scratchboxthree
+   \scratchtopoffset   \scratchheight
+   \scratchbottomoffset\scratchdepth
+   \scratchdimen\mathstackersparameter\c!minheight\relax
+   \ifdim\scratchheight<\scratchdimen
+     \scratchheight\scratchdimen
+     \ht\scratchboxthree\scratchheight
+   \fi
+   \scratchdimen\mathstackersparameter\c!mindepth\relax
+   \ifdim\scratchdepth<\scratchdimen
+     \scratchdepth\scratchdimen
+     \dp\scratchboxthree\scratchdepth
+   \fi
+   \advance\scratchtopoffset   -\scratchheight
+   \advance\scratchbottomoffset-\scratchdepth
+   \ifdim\scratchtopoffset<\zeropoint
+     \scratchtopoffset\zeropoint
+   \fi
+   \ifdim\scratchbottomoffset<\zeropoint
+     \scratchbottomoffset\zeropoint
+   \fi}
+
+\unexpanded\def\math_stackers_triplet#method#category#codepoint#toptext#bottomtext%
+  {\begingroup
+   \edef\currentmathstackers{#category}%
+   \mathstackersparameter\c!left\relax
+   \ifmmode\mathrel\else\dontleavehmode\fi
+     {\edef\p_offset  {\mathstackersparameter\c!offset}%
+      \edef\p_location{\mathstackersparameter\c!location}%
+      \edef\p_order   {\mathstackersparameter\c!order}%
+      \ifx\p_order\v!reverse
+        \edef\m_math_stackers_text_top   {#bottomtext}%
+        \edef\m_math_stackers_text_bottom{#toptext}%
+      \else
+        \edef\m_math_stackers_text_top   {#toptext}%
+        \edef\m_math_stackers_text_bottom{#bottomtext}%
+      \fi
+      \scratchleftoffset \zeropoint
+      \scratchrightoffset\zeropoint
+      \ifx\m_math_stackers_text_top\empty
+        \setbox\scratchboxone\emptyhbox
+      \else
+        \setmathsmalltextbox\scratchboxone\hbox{\math_stackers_toptext}%
+      \fi
+      \ifx\m_math_stackers_text_bottom\empty
+        \setbox\scratchboxtwo\emptyhbox
+      \else
+        \setmathsmalltextbox\scratchboxtwo\hbox{\math_stackers_bottomtext}%
+      \fi
+      %
+      \ifcase#method\relax
+        \math_stackers_check_unicode{#codepoint}%
+        \scratchwidth\wd
+          \ifdim\wd\scratchboxone>\wd\scratchboxtwo
+            \scratchboxone
+          \else
+            \scratchboxtwo
+          \fi
+        \relax
+      \else
+        \edef\m_math_stackers_text_middle{#codepoint}%
+        \ifx\m_math_stackers_text_middle\empty
+          \setbox\scratchboxthree\emptyhbox
+        \else
+          \setmathtextbox\scratchboxthree\hbox{\math_stackers_middletext}%
+        \fi
+        \scratchwidth\wd
+          \ifdim\wd\scratchboxone>\wd\scratchboxtwo
+            \scratchboxone
+          \else\ifdim\wd\scratchboxtwo>\wd\scratchboxthree
+            \scratchboxtwo
+          \else
+            \scratchboxthree
+          \fi\fi
+        \relax
+      \fi
+      %
+      \scratchdimen\mathstackersparameter\c!minwidth\relax
+      \ifdim\scratchwidth<\scratchdimen
+         \scratchwidth\scratchdimen
+      \fi
+      \advance\scratchwidth2\scratchhoffset
+      %
+      \ifcase#method\relax
+        \setbox\scratchboxthree\math_stackers_content
+      \fi
+      %
+      \ifdim\wd\scratchboxone<\scratchwidth
+        \setbox\scratchboxone\hbox to \scratchwidth{\hss\box\scratchboxone\hss}%
+      \fi
+      \ifdim\wd\scratchboxtwo<\scratchwidth
+        \setbox\scratchboxtwo\hbox to \scratchwidth{\hss\box\scratchboxtwo\hss}%
+      \fi
+      \ifdim\wd\scratchboxthree<\scratchwidth
+        \setbox\scratchboxthree\hbox to \scratchwidth{\hss\box\scratchboxthree\hss}%
+      \fi
+      %
+      \ifcsname\??mathstackerslocation\p_location\endcsname
+        \ifcase\csname\??mathstackerslocation\p_location\endcsname\relax
+          \scratchdistance\zeropoint
+        \or
+          % top
+          \scratchdistance\zeropoint
+        \or
+          % high
+          \scratchdistance.25\htdp\scratchboxthree
+        \or
+          % centered
+          \scratchdistance.5\htdp\scratchboxthree
+        \or
+          % low
+          \scratchdistance.75\htdp\scratchboxthree
+        \or
+          % bottom
+          \scratchdistance\htdp\scratchboxthree
+        \else
+          \scratchdistance\zeropoint
+        \fi
+      \else
+        \scratchdistance\p_location\htdp\scratchboxthree
+      \fi
+      %
+      \ifzeropt\scratchdistance\else
+        \setbox\scratchboxthree\hbox{\lower\scratchdistance\box\scratchboxthree}%
+      \fi
+      %
+      \math_stackers_normalize_three
+      %
+      \math_stackers_middle\bgroup
+        \box\scratchboxthree
+      \egroup
+      %
+      \ifdim\htdp\scratchboxone>\zeropoint
+        \scratchoffset\dimexpr\scratchvoffset
+        \kern-\scratchwidth
+        \math_stackers_top\bgroup
+          \raise\dimexpr\dp\scratchboxone+\scratchheight+\scratchoffset+\scratchtopoffset\relax
+          \box\scratchboxone
+        \egroup
+      \fi
+      %
+      \ifdim\htdp\scratchboxtwo>\zeropoint
+        \scratchoffset\dimexpr\scratchvoffset
+        \kern-\scratchwidth
+        \math_stackers_bottom\bgroup
+          \lower\dimexpr\ht\scratchboxtwo+\scratchdepth+\scratchoffset+\scratchbottomoffset\relax
+          \box\scratchboxtwo
+        \egroup
+      \fi}%
+  \mathstackersparameter\c!right\relax
+  \endgroup}
+
+\unexpanded\def\definemathextensible
+  {\dotripleempty\math_stackers_define_normal}
+
+\def\math_stackers_define_normal[#1][#2][#3]% category name unicode
+  {\ifthirdargument
+     \setuevalue{#2}{\math_stackers_auto_normal{#1}{\number#3}}%
+   \else
+     \setuevalue{#1}{\math_stackers_auto_normal\noexpand\currentmathstackers{\number#2}}%
+   \fi}
+
+\unexpanded\def\math_stackers_auto_normal#category#codepoint%
+  {\begingroup
+   \edef\currentmathstackers{#category}%
+   \scratchcounter#codepoint\relax
+   \dosingleempty\math_stackers_auto_normal_first}
+
+\unexpanded\def\math_stackers_auto_normal_first[#category]% [#2]% #2 gobble spaces
+  {\iffirstargument\edef\currentmathstackers{#category}\fi
+   \permitspacesbetweengroups
+   \dodoublegroupempty\math_stackers_auto_normal_second}
+
+\def\math_stackers_auto_normal_second#toptext#bottomtext%
+  {\math_stackers_triplet\zerocount\currentmathstackers\scratchcounter{#toptext}{#bottomtext}%
+   \endgroup}
+
+%D A few direct accessors:
+
+\unexpanded\def\mathextensible{\begingroup\dosingleempty\math_stackers_handle_math}
+\unexpanded\def\textextensible{\begingroup\dosingleempty\math_stackers_handle_text}
+
+\unexpanded\def\math_stackers_handle_math[#category]%
+  {\math_stackers_handle_extensible{\iffirstargument#category\else\v!mathematics\fi}} % will be defined later on
+
+\unexpanded\def\math_stackers_handle_text[#category]%
+  {\math_stackers_handle_extensible{\iffirstargument#category\else\v!text       \fi}} % will be defined later on
+
+\def\math_stackers_handle_extensible#category#codepoint#toptext#bottomtext%
+  {\math_stackers_triplet\zerocount{#category}{#codepoint}{#toptext}{#bottomtext}%
+   \endgroup}
+
+%D The next one deals with under and over extensibles (arrows mostly):
+
+\unexpanded\def\math_stackers_double#where#category#codepoint#text%
+  {\begingroup
+   \edef\currentmathstackers{#category}%
+   \mathstackersparameter\c!left\relax
+   \ifmmode\mathrel\else\dontleavehmode\fi
+     {\edef\currentmathstackers{#category}%
+      \edef\m_math_stackers_text_middle {#text}%
+      %
+      \edef\p_offset  {\mathstackersparameter\c!offset}%
+      \edef\p_location{\mathstackersparameter\c!location}%
+      %
+      \scratchleftoffset \zeropoint
+      \scratchrightoffset\zeropoint
+      %
+      \math_stackers_check_unicode{#codepoint}%
+      %
+      \ifx\currentmathtext\empty
+        \setbox\scratchboxthree\emptyhbox
+      \else
+        \setmathsmalltextbox\scratchboxthree\hbox{\math_stackers_middletext}%
+      \fi
+      \scratchwidth\wd\scratchboxthree
+      %
+      \scratchdimen\mathstackersparameter\c!minwidth\relax
+      \ifdim\scratchwidth<\scratchdimen
+         \scratchwidth\scratchdimen
+      \fi
+      \advance\scratchwidth2\scratchhoffset
+      %
+      \setbox\scratchboxtwo  \math_stackers_content
+      \setbox\scratchboxthree\hbox to \scratchwidth{\hss\box\scratchboxthree\hss}%
+      %
+      \math_stackers_normalize_three
+      %
+      \math_stackers_middle\bgroup
+        \box\scratchboxthree
+      \egroup
+      %
+      \ifdim\htdp\scratchboxtwo>\zeropoint
+        \kern-\scratchwidth
+        \ifcase#where\relax
+          \math_stackers_top\bgroup
+            \raise\dimexpr\scratchheight+\scratchtopoffset\relax
+            \box\scratchboxtwo
+          \egroup
+        \else
+          \math_stackers_bottom\bgroup
+            \lower\dimexpr\scratchdepth+\ht\scratchboxtwo+\scratchbottomoffset\relax
+            \box\scratchboxtwo
+          \egroup
+        \fi
+      \fi}%
+  \mathstackersparameter\c!right\relax
+  \endgroup}
+
+\unexpanded\def\definemathoverextensible {\dotripleempty\math_extensiblies_define_over }
+\unexpanded\def\definemathunderextensible{\dotripleempty\math_extensiblies_define_under}
+
+\def\math_extensiblies_define_over[#1][#2][#3]%
+  {\ifthirdargument
+     \setuevalue{#2}{\math_stackers_double\zerocount{#1}{\number#3}}%
+   \else
+     \setuevalue{#1}{\math_stackers_double\zerocount\noexpand\currentmathstackers{\number#2}}%
+   \fi}
+
+\def\math_extensiblies_define_under[#1][#2][#3]%
+  {\ifthirdargument
+     \setuevalue{#2}{\math_stackers_double\plusone{#1}{\number#3}}%
+   \else
+     \setuevalue{#1}{\math_stackers_double\plusone\noexpand\currentmathstackers{\number#2}}%
+   \fi}
+
+\unexpanded\def\mathover {\begingroup\dosingleempty\math_stackers_handle_over }
+\unexpanded\def\mathunder{\begingroup\dosingleempty\math_stackers_handle_under}
+
+\def\math_stackers_handle_over[#category]%
+  {\math_stackers_handle_double\zerocount{\iffirstargument#category\else\v!top   \fi}} % will be defined later on
+
+\def\math_stackers_handle_under[#category]#codepoint#bottomtext%
+  {\math_stackers_handle_double\plusone  {\iffirstargument#category\else\v!bottom\fi}} % will be defined later on
+
+\def\math_stackers_handle_double#location#category#codepoint#text%
+  {\math_stackers_double#location{#category}{#codepoint}{#text}%
+   \endgroup}
+
+%D Here is a bonus macro that takes three texts. It can be used to get consistent
+%D mixed usage.
+
+\unexpanded\def\mathtriplet
+  {\begingroup
+   \dosingleempty\math_stackers_handle_triplet}
+
+\def\math_stackers_handle_triplet[#category]#middletext#toptext#bottomtext%
+  {\math_stackers_triplet\plusone{\iffirstargument#category\else\currentmathstackers\fi}{#middletext}{#toptext}{#bottomtext}%
+   \endgroup}
+
+\unexpanded\def\definemathtriplet
+  {\dotripleempty\math_stackers_define_triplet}
+
+\def\math_stackers_define_triplet[#1][#2][#3]% category name default
+  {\ifthirdargument
+     \setuevalue{#2}{\math_stackers_auto_triplet_yes{#1}{#3}}%
+   \else\ifsecondargument
+     \setuevalue{#2}{\math_stackers_auto_triplet_nop{#1}}%
+   \else
+     \setuevalue{#1}{\math_stackers_auto_triplet_nop\noexpand\currentmathstackers}%
+   \fi\fi}
+
+\unexpanded\def\math_stackers_auto_triplet_yes#category#middletext%
+  {\begingroup
+   \edef\currentmathstackers  {#category}%
+   \def \m_math_stackers_text_middle{#middletext}%
+   \dosingleempty\math_stackers_auto_triplet_yes_first}
+
+\unexpanded\def\math_stackers_auto_triplet_yes_first[#category]% [#2]% #2 gobble spaces
+  {\iffirstargument\edef\currentmathstackers{#category}\fi
+   \permitspacesbetweengroups
+   \dodoublegroupempty\math_stackers_auto_triplet_yes_second}
+
+\def\math_stackers_auto_triplet_yes_second#toptext#bottomtext%
+  {\math_stackers_triplet\plusone\currentmathstackers\m_math_stackers_text_middle{#toptext}{#bottomtext}%
+   \endgroup}
+
+\unexpanded\def\math_stackers_auto_triplet_nop#category%
+  {\begingroup
+   \edef\currentmathstackers{#category}%
+   \dosingleempty\math_stackers_auto_triplet_nop_first}
+
+\unexpanded\def\math_stackers_auto_triplet_nop_first[#category]% [#2]% #2 gobble spaces
+  {\iffirstargument\edef\currentmathstackers{#category}\fi
+   \permitspacesbetweengroups
+   \dotriplegroupempty\math_stackers_auto_triplet_nop_second}
+
+\def\math_stackers_auto_triplet_nop_second#middletext#toptext#bottomtext%
+  {\math_stackers_triplet\plusone\currentmathstackers{#middletext}{#toptext}{#bottomtext}%
+   \endgroup}
+
+%D Definitions:
+
+\definemathstackers
+  [\v!mathematics]
+  [\c!topcommand=\mathematics,
+   \c!middlecommand=\mathematics,
+   \c!bottomcommand=\mathematics]
+
+\definemathstackers
+  [\s!math]
+  [\v!mathematics]
+
+\definemathstackers
+  [\v!text]
+  [\v!mathematics]
+  [\c!topcommand=,
+   \c!middlecommand=\mathematics,
+   \c!bottomcommand=]
+
+\definemathstackers
+  [\v!reverse]
+  [\v!mathematics]
+  [\c!order=\v!reverse]
+
+\definemathstackers
+  [\v!top]
+  [\v!mathematics]
+  [\c!location=\v!top,
+   \c!middlecommand=\mathematics,
+   \c!hoffset=\zeropoint]
+
+\definemathstackers
+  [\v!bottom]
+  [\v!mathematics]
+  [\c!location=\v!top,
+   \c!middlecommand=\mathematics,
+   \c!hoffset=\zeropoint]
+
+% These are compatibity definitions, math only.
+
+\definemathstackers [\v!none]   [\v!mathematics] [\c!hoffset=\zeropoint]
+\definemathstackers [\v!normal] [\v!mathematics] [\c!hoffset=0.5\emwidth] % the default
+\definemathstackers [\v!small]  [\v!mathematics] [\c!hoffset=1\emwidth]
+\definemathstackers [\v!medium] [\v!mathematics] [\c!hoffset=1.5\emwidth]
+\definemathstackers [\v!big]    [\v!mathematics] [\c!hoffset=2\emwidth]
+
+\definemathextensible [\v!reverse] [xrel]                ["002D]
+\definemathextensible [\v!reverse] [xequal]              ["003D]
+\definemathextensible [\v!reverse] [xleftarrow]          ["2190]
+\definemathextensible [\v!reverse] [xrightarrow]         ["2192]
+\definemathextensible [\v!reverse] [xtwoheadleftarrow]   ["219E]
+\definemathextensible [\v!reverse] [xtwoheadrightarrow]  ["21A0]
+\definemathextensible [\v!reverse] [xmapsto]             ["21A6]
+\definemathextensible [\v!reverse] [xhookleftarrow]      ["21A9]
+\definemathextensible [\v!reverse] [xhookrightarrow]     ["21AA]
+\definemathextensible [\v!reverse] [xleftharpoondown]    ["21BD]
+\definemathextensible [\v!reverse] [xleftharpoonup]      ["21BC]
+\definemathextensible [\v!reverse] [xrightharpoondown]   ["21C1]
+\definemathextensible [\v!reverse] [xrightharpoonup]     ["21C0]
+\definemathextensible [\v!reverse] [xrightoverleftarrow] ["21C4]
+\definemathextensible [\v!reverse] [xleftrightharpoons]  ["21CB]
+\definemathextensible [\v!reverse] [xrightleftharpoons]  ["21CC]
+\definemathextensible [\v!reverse] [xtriplerel]          ["2261]
+\definemathextensible [\v!reverse] [xleftrightarrow]     ["27F7]
+\definemathextensible [\v!reverse] [xLeftarrow]          ["27F8]
+\definemathextensible [\v!reverse] [xRightarrow]         ["27F9]
+\definemathextensible [\v!reverse] [xLeftrightarrow]     ["27FA]
+
+\definemathextensible [\v!mathematics] [mrel]                ["002D]
+\definemathextensible [\v!mathematics] [mequal]              ["003D]
+\definemathextensible [\v!mathematics] [mleftarrow]          ["2190]
+\definemathextensible [\v!mathematics] [mrightarrow]         ["2192]
+\definemathextensible [\v!mathematics] [mtwoheadleftarrow]   ["219E]
+\definemathextensible [\v!mathematics] [mtwoheadrightarrow]  ["21A0]
+\definemathextensible [\v!mathematics] [mmapsto]             ["21A6]
+\definemathextensible [\v!mathematics] [mhookleftarrow]      ["21A9]
+\definemathextensible [\v!mathematics] [mhookrightarrow]     ["21AA]
+\definemathextensible [\v!mathematics] [mleftharpoondown]    ["21BD]
+\definemathextensible [\v!mathematics] [mleftharpoonup]      ["21BC]
+\definemathextensible [\v!mathematics] [mrightharpoondown]   ["21C1]
+\definemathextensible [\v!mathematics] [mrightharpoonup]     ["21C0]
+\definemathextensible [\v!mathematics] [mrightoverleftarrow] ["21C4]
+\definemathextensible [\v!mathematics] [mleftrightharpoons]  ["21CB]
+\definemathextensible [\v!mathematics] [mrightleftharpoons]  ["21CC]
+\definemathextensible [\v!mathematics] [mtriplerel]          ["2261]
+\definemathextensible [\v!mathematics] [mleftrightarrow]     ["27F7]
+\definemathextensible [\v!mathematics] [mLeftarrow]          ["27F8]
+\definemathextensible [\v!mathematics] [mRightarrow]         ["27F9]
+\definemathextensible [\v!mathematics] [mLeftrightarrow]     ["27FA]
+
+\definemathextensible [\v!text] [trel]                ["002D]
+\definemathextensible [\v!text] [tequal]              ["003D]
+\definemathextensible [\v!text] [tleftarrow]          ["2190]
+\definemathextensible [\v!text] [trightarrow]         ["2192]
+\definemathextensible [\v!text] [ttwoheadleftarrow]   ["219E]
+\definemathextensible [\v!text] [ttwoheadrightarrow]  ["21A0]
+\definemathextensible [\v!text] [tmapsto]             ["21A6]
+\definemathextensible [\v!text] [thookleftarrow]      ["21A9]
+\definemathextensible [\v!text] [thookrightarrow]     ["21AA]
+\definemathextensible [\v!text] [tleftharpoondown]    ["21BD]
+\definemathextensible [\v!text] [tleftharpoonup]      ["21BC]
+\definemathextensible [\v!text] [trightharpoondown]   ["21C1]
+\definemathextensible [\v!text] [trightharpoonup]     ["21C0]
+\definemathextensible [\v!text] [trightoverleftarrow] ["21C4]
+\definemathextensible [\v!text] [tleftrightharpoons]  ["21CB]
+\definemathextensible [\v!text] [trightleftharpoons]  ["21CC]
+\definemathextensible [\v!text] [ttriplerel]          ["2261]
+\definemathextensible [\v!text] [tleftrightarrow]     ["27F7]
+\definemathextensible [\v!text] [tLeftarrow]          ["27F8]
+\definemathextensible [\v!text] [tRightarrow]         ["27F9]
+\definemathextensible [\v!text] [tLeftrightarrow]     ["27FA]
+
+\definemathoverextensible [\v!top] [overleftarrow]         ["2190]
+\definemathoverextensible [\v!top] [overrightarrow]        ["2192]
+\definemathoverextensible [\v!top] [overleftharpoondown]   ["21BD]
+\definemathoverextensible [\v!top] [overleftharpoonup]     ["21BC]
+\definemathoverextensible [\v!top] [overrightharpoondown]  ["21C1]
+\definemathoverextensible [\v!top] [overrightharpoonup]    ["21C0]
+\definemathoverextensible [\v!top] [overleftrightarrow]    ["27F7]
+\definemathoverextensible [\v!top] [overtwoheadleftarrow]  ["27F8]
+\definemathoverextensible [\v!top] [overtwoheadrightarrow] ["27F9]
+
+\definemathunderextensible [\v!bottom] [underleftarrow]         ["2190]
+\definemathunderextensible [\v!bottom] [underrightarrow]        ["2192]
+\definemathunderextensible [\v!bottom] [underleftharpoondown]   ["21BD]
+\definemathunderextensible [\v!bottom] [underleftharpoonup]     ["21BC]
+\definemathunderextensible [\v!bottom] [underrightharpoondown]  ["21C1]
+\definemathunderextensible [\v!bottom] [underrightharpoonup]    ["21C0]
+\definemathunderextensible [\v!bottom] [underleftrightarrow]    ["27F7]
+\definemathunderextensible [\v!bottom] [undertwoheadleftarrow]  ["27F8]
+\definemathunderextensible [\v!bottom] [undertwoheadrightarrow] ["27F9]
+
+%D Some bonus ones (for the moment here):
+
+\definemathstackers
+  [\v!chemistry]
+  [\c!offset=\v!max,
+   \c!left=\enspace,
+   \c!right=\enspace,
+   \c!hoffset=.5\emwidth]
+
+\definemathextensible [\v!chemistry] [cleftarrow]          ["2190]
+\definemathextensible [\v!chemistry] [crightarrow]         ["2192]
+\definemathextensible [\v!chemistry] [crightoverleftarrow] ["21C4]
+
+% for the moment:
+
+\def\math_stackers_hacked_fill#1#2#3%
+  {\mathematics
+     {\begingroup
+      \mathsurround\zeropoint
+      \thickmuskip \zeromuskip
+      \medmuskip   \zeromuskip
+      \thinmuskip  \zeromuskip
+      #1%
+      \mkern-7\onemuskip
+      \cleaders\mathstylehbox{\mkern-2\onemuskip#2\mkern-2\onemuskip}\hfill
+      \mkern-7\onemuskip
+      #3%
+      \endgroup}}
+
+\unexpanded\def\rightarrowfill        {\math_stackers_hacked_fill \relbar                   \relbar                      \rightarrow}
+\unexpanded\def\leftarrowfill         {\math_stackers_hacked_fill \leftarrow                \relbar                      \relbar    }
+\unexpanded\def\rightoverleftarrowfill{\math_stackers_hacked_fill \ctxdoublearrowfillleftend\ctxdoublearrowfillmiddlepart\ctxdoublearrowfillrightend}
+\unexpanded\def\equalfill             {\math_stackers_hacked_fill \Relbar                   \Relbar                      \Relbar}
+\unexpanded\def\Rightarrowfill        {\math_stackers_hacked_fill \Relbar                   \Relbar                      \Rightarrow}
+\unexpanded\def\Leftarrowfill         {\math_stackers_hacked_fill \Leftarrow                \Relbar                      \Relbar}
+\unexpanded\def\Leftrightarrowfill    {\math_stackers_hacked_fill \Leftarrow                \Relbar                      \Rightarrow}
+\unexpanded\def\leftrightarrowfill    {\math_stackers_hacked_fill \leftarrow                \relbar                      \rightarrow}
+\unexpanded\def\mapstofill            {\math_stackers_hacked_fill{\mapstochar\relbar}       \relbar                      \rightarrow}
+\unexpanded\def\twoheadrightarrowfill {\math_stackers_hacked_fill \relbar                   \relbar                      \twoheadrightarrow}
+\unexpanded\def\twoheadleftarrowfill  {\math_stackers_hacked_fill \twoheadleftarrow         \relbar                      \relbar}
+\unexpanded\def\rightharpoondownfill  {\math_stackers_hacked_fill \relbar                   \relbar                      \rightharpoondown}
+\unexpanded\def\rightharpoonupfill    {\math_stackers_hacked_fill \relbar                   \relbar                      \rightharpoonup}
+\unexpanded\def\leftharpoondownfill   {\math_stackers_hacked_fill \leftharpoondown          \relbar                      \relbar}
+\unexpanded\def\leftharpoonupfill     {\math_stackers_hacked_fill \leftharpoonup            \relbar                      \relbar}
+\unexpanded\def\hookleftfill          {\math_stackers_hacked_fill \leftarrow                \relbar                     {\relbar\joinrel\rhook}}
+\unexpanded\def\hookrightfill         {\math_stackers_hacked_fill{\lhook\joinrel\relbar}    \relbar                      \rightarrow}
+\unexpanded\def\relfill               {\math_stackers_hacked_fill \relbar                   \relbar                      \relbar}
+\unexpanded\def\triplerelfill         {\math_stackers_hacked_fill \equiv                    \equiv                       \equiv}
+
+\unexpanded\def\singlebond            {{\xrel}} % or \def\singlebond{{\xrel[2]}}
+\unexpanded\def\doublebond            {{\xequal}}
+\unexpanded\def\triplebond            {{\xtriplerel}}
+
+\unexpanded\def\defineextensiblefiller
+  {\dodoubleargument\math_stackers_define_filler}
+
+\def\math_stackers_define_filler[#1][#2]%
+  {\setuevalue{#1}{\leaders\number#2\hfill}}
+
+%D For the moment:
+
+\def\math_stackers_define_filler[#1][#2]%
+  {\expandafter\let\csname\??mathextensiblefallbacks\number#2\expandafter\endcsname\csname#1\endcsname
+   \expandafter\let\csname                                 #1\expandafter\endcsname\csname#1\endcsname}
+
+\defineextensiblefiller [relfill]                ["002D]
+\defineextensiblefiller [equalfill]              ["003D]
+\defineextensiblefiller [leftarrowfill]          ["2190]
+\defineextensiblefiller [rightarrowfill]         ["2192]
+\defineextensiblefiller [twoheadleftarrowfill]   ["219E]
+\defineextensiblefiller [twoheadrightarrowfill]  ["21A0]
+\defineextensiblefiller [mapstofill]             ["21A6]
+\defineextensiblefiller [hookleftarrowfill]      ["21A9]
+\defineextensiblefiller [hookrightarrowfill]     ["21AA]
+\defineextensiblefiller [leftharpoondownfill]    ["21BD]
+\defineextensiblefiller [leftharpoonupfill]      ["21BC]
+\defineextensiblefiller [rightharpoondownfill]   ["21C1]
+\defineextensiblefiller [rightharpoonupfill]     ["21C0]
+\defineextensiblefiller [rightoverleftarrowfill] ["21C4]
+\defineextensiblefiller [leftrightharpoonsfill]  ["21CB]
+\defineextensiblefiller [rightleftharpoonsfill]  ["21CC]
+\defineextensiblefiller [triplerelfill]          ["2261]
+\defineextensiblefiller [leftrightarrowfill]     ["27F7]
+\defineextensiblefiller [Leftarrowfill]          ["27F8]
+\defineextensiblefiller [Rightarrowfill]         ["27F9]
+\defineextensiblefiller [Leftrightarrowfill]     ["27FA]
+
+%D Extra:
+
+\unexpanded\edef\singlebond{\mathematics{\mathsurround\zeropoint\char\number"002D}}
+\unexpanded\edef\doublebond{\mathematics{\mathsurround\zeropoint\char\number"003D}}
+\unexpanded\edef\triplebond{\mathematics{\mathsurround\zeropoint\char\number"2261}}
+
+% \mathchardef\singlebond"002D
+% \mathchardef\doublebond"003D
+% \mathchardef\triplebond"2261
+
+\protect \endinput
+
+% \mathrel{\mathop{\hbox to \dimen0{\hss\copy4\hss}}
+% \limits\normalsuperscript{\box0}\normalsubscript{\box2}}%
+
+% $\Uoverdelimiter \defaultmathfamily "2194 {xxxx}$
+% $\Udelimiterover \defaultmathfamily "2194 {xxxx}$
+% $\Uunderdelimiter\defaultmathfamily "2194 {xxxx}$
+% $\Udelimiterunder\defaultmathfamily "2194 {xxxx}$
+% $\Udelimiterover \defaultmathfamily "219A {\Udelimiterunder \defaultmathfamily "219B {xxxx}}$
+
+% $a \mathrel{\mathop{\filledhboxr{mid}}}\limits^{\filledhboxg{\strut top}}_{\filledhboxb{\strut bottom}} b$
diff --git a/tex/context/base/math-ttv.lua b/tex/context/base/math-ttv.lua
index be7d1949b..74f8a2a7b 100644
--- a/tex/context/base/math-ttv.lua
+++ b/tex/context/base/math-ttv.lua
@@ -714,8 +714,8 @@ mathencodings["tex-mb"] = {
     [0x003DC] = 0x7A, -- Digamma               \digamma
     [0x003F0] = 0x7B, -- kappa                 \varkappa
     [0x1D55C] = 0x7C, -- k                     \Bbbk (blackboard k)
-    [0x0210F] = 0x7D, -- planckover2pi         \hslash
-    [0x00127] = 0x7E, -- planckover2pi1        \hbar
+    [0x0210F] = 0x7D, -- planckover2pi         \hslash % 0x7D
+    [0x00127] = 0x7E, -- planckover2pi1        \hbar   % 0x7E
     [0x003F6] = 0x7F, -- epsiloninv            \backepsilon
 }
 
diff --git a/tex/context/base/math-vfu.lua b/tex/context/base/math-vfu.lua
index 317924a41..b5ee71e62 100644
--- a/tex/context/base/math-vfu.lua
+++ b/tex/context/base/math-vfu.lua
@@ -92,21 +92,21 @@ local function brace(main,characters,id,size,unicode,first,rule,left,right,rule,
     end
 end
 
-local function arrow(main,characters,id,size,unicode,arrow,minus,isleft)
+local function extension(main,characters,id,size,unicode,first,middle,last)
     local chr = characters[unicode]
     if not chr then
-        -- skip
-    elseif isleft then
-        chr.horiz_variants = {
-            { extender = 0, glyph = arrow },
-            { extender = 1, glyph = minus },
-        }
-    else
-        chr.horiz_variants = {
-            { extender = 1, glyph = minus },
-            { extender = 0, glyph = arrow },
-        }
+        return -- skip
     end
+    local fw = characters[first ].width
+    local mw = characters[middle].width
+    local lw = characters[last  ].width
+    if fw == 0 then fw = 1 end
+    if lw == 0 then lw = 1 end
+    chr.horiz_variants = {
+        { extender = 0, glyph = first,  ["end"] = fw/2, start = 0,    advance = fw },
+        { extender = 1, glyph = middle, ["end"] = mw/2, start = mw/2, advance = mw },
+        { extender = 0, glyph = last,   ["end"] = 0,    start = lw/2, advance = lw },
+    }
 end
 
 local function parent(main,characters,id,size,unicode,first,rule,last)
@@ -150,14 +150,24 @@ local function make(main,characters,id,size,n,m)
     end
 end
 
-local function minus(main,characters,id,size,unicode) -- push/pop needed?
-    local minus = characters[0x002D]
+local function clipped(main,characters,id,size,unicode,original) -- push/pop needed?
+    local minus = characters[original]
     if minus then
         local mu = size/18
-        local width = minus.width - 5*mu
+        local step = 3*mu
+        local width = minus.width
+        if width > step then
+            width = width - step
+            step = step / 2
+        else
+            width = width / 2
+            step = width
+        end
         characters[unicode] = {
-            width = width, height = minus.height, depth = minus.depth,
-            commands = { push, { "right", -3*mu }, { "slot", id, 0x002D }, pop }
+            width    = width,
+            height   = minus.height,
+            depth    = minus.depth,
+            commands = { push, { "right", -step }, { "slot", id, original }, pop }
         }
     end
 end
@@ -290,20 +300,20 @@ local function vertbar(main,characters,id,size,parent,scale,unicode)
     end
 end
 
-local function jointwo(main,characters,id,size,unicode,u1,d12,u2)
+local function jointwo(main,characters,id,size,unicode,u1,d12,u2,what)
     local c1, c2 = characters[u1], characters[u2]
     if c1 and c2 then
         local w1, w2 = c1.width, c2.width
         local mu = size/18
         characters[unicode] = {
-            width    = w1 + w2 - d12*mu,
+            width    = w1 + w2 - d12 * mu,
             height   = max(c1.height or 0, c2.height or 0),
-            depth    = max(c1.depth or 0, c2.depth or 0),
+            depth    = max(c1.depth  or 0, c2.depth  or 0),
             commands = {
                 { "slot", id, u1 },
                 { "right", -d12*mu } ,
                 { "slot", id, u2 },
-            }
+            },
         }
     end
 end
@@ -388,19 +398,20 @@ function vfmath.addmissing(main,id,size)
     for i=0x7A,0x7D do
         make(main,characters,id,size,i,1)
     end
+
     brace    (main,characters,id,size,0x23DE,0xFF17A,0xFF301,0xFF17D,0xFF17C,0xFF301,0xFF17B)
     brace    (main,characters,id,size,0x23DF,0xFF27C,0xFF401,0xFF27B,0xFF27A,0xFF401,0xFF27D)
+
     parent   (main,characters,id,size,0x23DC,0xFF17A,0xFF301,0xFF17B)
     parent   (main,characters,id,size,0x23DD,0xFF27C,0xFF401,0xFF27D)
+
  -- negate   (main,characters,id,size,0x2260,0x003D)
     dots     (main,characters,id,size,0x2026) -- ldots
     dots     (main,characters,id,size,0x22EE) -- vdots
     dots     (main,characters,id,size,0x22EF) -- cdots
     dots     (main,characters,id,size,0x22F1) -- ddots
     dots     (main,characters,id,size,0x22F0) -- udots
-    minus    (main,characters,id,size,0xFF501)
-    arrow    (main,characters,id,size,0x2190,0x2190,0xFF501,true)  -- left
-    arrow    (main,characters,id,size,0x2192,0x2192,0xFF501,false) -- right
+
     vertbar  (main,characters,id,size,0x0007C,0.10,0xFF601) -- big  : 0.85 bodyfontsize
     vertbar  (main,characters,id,size,0xFF601,0.30,0xFF602) -- Big  : 1.15 bodyfontsize
     vertbar  (main,characters,id,size,0xFF602,0.30,0xFF603) -- bigg : 1.45 bodyfontsize
@@ -409,24 +420,69 @@ function vfmath.addmissing(main,id,size)
     vertbar  (main,characters,id,size,0xFF605,0.30,0xFF606)
     vertbar  (main,characters,id,size,0xFF606,0.30,0xFF607)
     vertbar  (main,characters,id,size,0xFF607,0.30,0xFF608)
+
+    clipped  (main,characters,id,size,0xFF501,0x0002D) -- minus
+    clipped  (main,characters,id,size,0xFF502,0x02190) -- lefthead
+    clipped  (main,characters,id,size,0xFF503,0x02192) -- righthead
+    clipped  (main,characters,id,size,0xFF504,0xFE321) -- mapsto
+    clipped  (main,characters,id,size,0xFF505,0xFE322) -- lhook
+    clipped  (main,characters,id,size,0xFF506,0xFE323) -- rhook
+    clipped  (main,characters,id,size,0xFF507,0xFE324) -- mapsfrom
+    clipped  (main,characters,id,size,0xFF508,0x021D0) -- double lefthead
+    clipped  (main,characters,id,size,0xFF509,0x021D2) -- double righthead
+    clipped  (main,characters,id,size,0xFF50A,0x0003D) -- equal
+    clipped  (main,characters,id,size,0xFF50B,0x0219E) -- lefttwohead
+    clipped  (main,characters,id,size,0xFF50C,0x021A0) -- righttwohead
+    clipped  (main,characters,id,size,0xFF50D,0xFF350) -- lr arrow combi snippet
+    clipped  (main,characters,id,size,0xFF50E,0xFF351) -- lr arrow combi snippet
+    clipped  (main,characters,id,size,0xFF50F,0xFF352) -- lr arrow combi snippet
+    clipped  (main,characters,id,size,0xFF510,0x02261) -- equiv
+
+    extension(main,characters,id,size,0x2190,0xFF502,0xFF501,0xFF501)                 -- \leftarrow
+    extension(main,characters,id,size,0x2192,0xFF501,0xFF501,0xFF503)                 -- \rightarrow
+
+    extension(main,characters,id,size,0x002D,0xFF501,0xFF501,0xFF501)                 -- \rel
+    extension(main,characters,id,size,0x003D,0xFF50A,0xFF50A,0xFF50A)                 -- \equal
+    extension(main,characters,id,size,0x2261,0xFF510,0xFF510,0xFF510)                 -- \equiv
+
     jointwo  (main,characters,id,size,0x21A6,0xFE321,0,0x02192)                       -- \mapstochar\rightarrow
     jointwo  (main,characters,id,size,0x21A9,0x02190,joinrelfactor,0xFE323)           -- \leftarrow\joinrel\rhook
     jointwo  (main,characters,id,size,0x21AA,0xFE322,joinrelfactor,0x02192)           -- \lhook\joinrel\rightarrow
-    stack    (main,characters,id,size,0x2259,0x0003D,3,0x02227)                       -- \buildrel\wedge\over=
-    jointwo  (main,characters,id,size,0x22C8,0x022B3,joinrelfactor,0x022B2)           -- \mathrel\triangleright\joinrel\mathrel\triangleleft (4 looks better than 3)
-    jointwo  (main,characters,id,size,0x2260,0x00338,0,0x0003D)                       -- \not\equal
-    jointwo  (main,characters,id,size,0x2284,0x00338,0,0x02282)                       -- \not\subset
-    jointwo  (main,characters,id,size,0x2285,0x00338,0,0x02283)                       -- \not\supset
-    jointwo  (main,characters,id,size,0x2209,0x00338,0,0x02208)                       -- \not\in
-    jointwo  (main,characters,id,size,0x22A7,0x0007C,joinrelfactor,0x0003D)           -- \mathrel|\joinrel=
     jointwo  (main,characters,id,size,0x27F5,0x02190,joinrelfactor,0x0002D)           -- \leftarrow\joinrel\relbar
-    jointwo  (main,characters,id,size,0x27F6,0x0002D,joinrelfactor,0x02192)           -- \relbar\joinrel\rightarrow
+    jointwo  (main,characters,id,size,0x27F6,0x0002D,joinrelfactor,0x02192,2)         -- \relbar\joinrel\rightarrow
     jointwo  (main,characters,id,size,0x27F7,0x02190,joinrelfactor,0x02192)           -- \leftarrow\joinrel\rightarrow
     jointwo  (main,characters,id,size,0x27F8,0x021D0,joinrelfactor,0x0003D)           -- \Leftarrow\joinrel\Relbar
     jointwo  (main,characters,id,size,0x27F9,0x0003D,joinrelfactor,0x021D2)           -- \Relbar\joinrel\Rightarrow
     jointwo  (main,characters,id,size,0x27FA,0x021D0,joinrelfactor,0x021D2)           -- \Leftarrow\joinrel\Rightarrow
     jointhree(main,characters,id,size,0x27FB,0x02190,joinrelfactor,0x0002D,0,0xFE324) -- \leftarrow\joinrel\relbar\mapsfromchar
     jointhree(main,characters,id,size,0x27FC,0xFE321,0,0x0002D,joinrelfactor,0x02192) -- \mapstochar\relbar\joinrel\rightarrow
+
+    extension(main,characters,id,size,0x21A6,0xFF504,0xFF501,0xFF503)                 -- \mapstochar\rightarrow
+    extension(main,characters,id,size,0x21A9,0xFF502,0xFF501,0xFF506)                 -- \leftarrow\joinrel\rhook
+    extension(main,characters,id,size,0x21AA,0xFF505,0xFF501,0xFF503)                 -- \lhook\joinrel\rightarrow
+    extension(main,characters,id,size,0x27F5,0xFF502,0xFF501,0xFF501)                 -- \leftarrow\joinrel\relbar
+    extension(main,characters,id,size,0x27F6,0xFF501,0xFF501,0xFF503)                 -- \relbar\joinrel\rightarrow
+    extension(main,characters,id,size,0x27F7,0xFF502,0xFF501,0xFF503)                 -- \leftarrow\joinrel\rightarrow
+    extension(main,characters,id,size,0x27F8,0xFF508,0xFF50A,0xFF50A)                 -- \Leftarrow\joinrel\Relbar
+    extension(main,characters,id,size,0x27F9,0xFF50A,0xFF50A,0xFF509)                 -- \Relbar\joinrel\Rightarrow
+    extension(main,characters,id,size,0x27FA,0xFF508,0xFF50A,0xFF509)                 -- \Leftarrow\joinrel\Rightarrow
+    extension(main,characters,id,size,0x27FB,0xFF502,0xFF501,0xFF507)                 -- \leftarrow\joinrel\relbar\mapsfromchar
+    extension(main,characters,id,size,0x27FC,0xFF504,0xFF501,0xFF503)                 -- \mapstochar\relbar\joinrel\rightarrow
+
+    extension(main,characters,id,size,0x219E,0xFF50B,0xFF501,0xFF501)                 -- \twoheadleftarrow\joinrel\relbar
+    extension(main,characters,id,size,0x21A0,0xFF501,0xFF501,0xFF50C)                 -- \relbar\joinrel\twoheadrightarrow
+    extension(main,characters,id,size,0x21C4,0xFF50D,0xFF50E,0xFF50F)                 -- leftoverright
+
+    -- 21CB leftrightharpoon
+    -- 21CC rightleftharpoon
+
+    stack    (main,characters,id,size,0x2259,0x0003D,3,0x02227)                       -- \buildrel\wedge\over=
+    jointwo  (main,characters,id,size,0x22C8,0x022B3,joinrelfactor,0x022B2)           -- \mathrel\triangleright\joinrel\mathrel\triangleleft (4 looks better than 3)
+    jointwo  (main,characters,id,size,0x22A7,0x0007C,joinrelfactor,0x0003D)           -- \mathrel|\joinrel=
+    jointwo  (main,characters,id,size,0x2260,0x00338,0,0x0003D)                       -- \not\equal
+    jointwo  (main,characters,id,size,0x2284,0x00338,0,0x02282)                       -- \not\subset
+    jointwo  (main,characters,id,size,0x2285,0x00338,0,0x02283)                       -- \not\supset
+    jointwo  (main,characters,id,size,0x2209,0x00338,0,0x02208)                       -- \not\in
     jointwo  (main,characters,id,size,0x2254,0x03A,0,0x03D)                           -- := (≔)
 
     repeated(main,characters,id,size,0x222C,0x222B,2,0xFF800,1/3)
diff --git a/tex/context/base/mult-de.mkii b/tex/context/base/mult-de.mkii
index 99a5944b0..3bf540b9f 100644
--- a/tex/context/base/mult-de.mkii
+++ b/tex/context/base/mult-de.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{kapitel}
 \setinterfacevariable{character}{buchstabe}
 \setinterfacevariable{characters}{buchstaben}
+\setinterfacevariable{chemistry}{chemistry}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{farbe}
 \setinterfacevariable{column}{column}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{unten}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{bottomcommand}
 \setinterfaceconstant{bottomdistance}{abstandunten}
 \setinterfaceconstant{bottomframe}{untenrahmen}
 \setinterfaceconstant{bottomoffset}{untenoffset}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{menue}
 \setinterfaceconstant{method}{methode}
 \setinterfaceconstant{middle}{mittig}
+\setinterfaceconstant{middlecommand}{middlecommand}
 \setinterfaceconstant{middlespeech}{middlespeech}
 \setinterfaceconstant{middletext}{mittigertext}
 \setinterfaceconstant{midsentence}{midsentence}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{toleranz}
 \setinterfaceconstant{top}{oben}
+\setinterfaceconstant{topcommand}{topcommand}
 \setinterfaceconstant{topdistance}{obenabstand}
 \setinterfaceconstant{topframe}{obenrahmen}
 \setinterfaceconstant{topoffset}{obenoffset}
diff --git a/tex/context/base/mult-def.lua b/tex/context/base/mult-def.lua
index 9c7b4f767..3c7700414 100644
--- a/tex/context/base/mult-def.lua
+++ b/tex/context/base/mult-def.lua
@@ -6630,6 +6630,18 @@ return {
    ["en"]="layout",
    ["nl"]="layout",
   },
+  ["topcommand"]={
+   ["en"]="topcommand",
+   ["nl"]="bovencommando",
+  },
+  ["middlecommand"]={
+   ["en"]="middlecommand",
+   ["nl"]="middencommando",
+  },
+  ["bottomcommand"]={
+   ["en"]="bottomcommand",
+   ["nl"]="ondercommando",
+  },
   ["action"]={
    ["cs"]="akce",
    ["de"]="aktion",
@@ -12586,6 +12598,10 @@ return {
    ["pe"]="حرفها",
    ["ro"]="caractere",
   },
+  ["chemistry"]={
+   ["en"]="chemistry",
+   ["nl"]="chemie",
+  },
   ["color"]={
    ["cs"]="barevne",
    ["de"]="farbe",
diff --git a/tex/context/base/mult-en.mkii b/tex/context/base/mult-en.mkii
index 24bf6c074..80d86546e 100644
--- a/tex/context/base/mult-en.mkii
+++ b/tex/context/base/mult-en.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{chapter}
 \setinterfacevariable{character}{character}
 \setinterfacevariable{characters}{characters}
+\setinterfacevariable{chemistry}{chemistry}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{color}
 \setinterfacevariable{column}{column}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{bottom}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{bottomcommand}
 \setinterfaceconstant{bottomdistance}{bottomdistance}
 \setinterfaceconstant{bottomframe}{bottomframe}
 \setinterfaceconstant{bottomoffset}{bottomoffset}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{menu}
 \setinterfaceconstant{method}{method}
 \setinterfaceconstant{middle}{middle}
+\setinterfaceconstant{middlecommand}{middlecommand}
 \setinterfaceconstant{middlespeech}{middlespeech}
 \setinterfaceconstant{middletext}{middletext}
 \setinterfaceconstant{midsentence}{midsentence}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{tolerance}
 \setinterfaceconstant{top}{top}
+\setinterfaceconstant{topcommand}{topcommand}
 \setinterfaceconstant{topdistance}{topdistance}
 \setinterfaceconstant{topframe}{topframe}
 \setinterfaceconstant{topoffset}{topoffset}
diff --git a/tex/context/base/mult-fr.mkii b/tex/context/base/mult-fr.mkii
index 0640cbecb..e68763dfc 100644
--- a/tex/context/base/mult-fr.mkii
+++ b/tex/context/base/mult-fr.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{chapitre}
 \setinterfacevariable{character}{caractere}
 \setinterfacevariable{characters}{caracteres}
+\setinterfacevariable{chemistry}{chemistry}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{couleur}
 \setinterfacevariable{column}{colonne}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{inf}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{bottomcommand}
 \setinterfaceconstant{bottomdistance}{distanceinf}
 \setinterfaceconstant{bottomframe}{cadreinf}
 \setinterfaceconstant{bottomoffset}{decalageinf}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{menu}
 \setinterfaceconstant{method}{methode}
 \setinterfaceconstant{middle}{milieu}
+\setinterfaceconstant{middlecommand}{middlecommand}
 \setinterfaceconstant{middlespeech}{middlespeech}
 \setinterfaceconstant{middletext}{textecentre}
 \setinterfaceconstant{midsentence}{midsentence}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{tolerance}
 \setinterfaceconstant{top}{sup}
+\setinterfaceconstant{topcommand}{topcommand}
 \setinterfaceconstant{topdistance}{distancesup}
 \setinterfaceconstant{topframe}{cadresup}
 \setinterfaceconstant{topoffset}{decalagesup}
diff --git a/tex/context/base/mult-it.mkii b/tex/context/base/mult-it.mkii
index f4d02ad46..e86a35b97 100644
--- a/tex/context/base/mult-it.mkii
+++ b/tex/context/base/mult-it.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{capitolo}
 \setinterfacevariable{character}{lettera}
 \setinterfacevariable{characters}{lettere}
+\setinterfacevariable{chemistry}{chemistry}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{colore}
 \setinterfacevariable{column}{colonna}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{fondo}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{bottomcommand}
 \setinterfaceconstant{bottomdistance}{distanzafondo}
 \setinterfaceconstant{bottomframe}{cornicefondo}
 \setinterfaceconstant{bottomoffset}{offsetfondo}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{menu}
 \setinterfaceconstant{method}{metodo}
 \setinterfaceconstant{middle}{centro}
+\setinterfaceconstant{middlecommand}{middlecommand}
 \setinterfaceconstant{middlespeech}{middlespeech}
 \setinterfaceconstant{middletext}{testocentro}
 \setinterfaceconstant{midsentence}{midsentence}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{tolleranza}
 \setinterfaceconstant{top}{cima}
+\setinterfaceconstant{topcommand}{topcommand}
 \setinterfaceconstant{topdistance}{distanzacima}
 \setinterfaceconstant{topframe}{cornicecima}
 \setinterfaceconstant{topoffset}{offsetcima}
diff --git a/tex/context/base/mult-low.lua b/tex/context/base/mult-low.lua
index 921a3062d..5e797590e 100644
--- a/tex/context/base/mult-low.lua
+++ b/tex/context/base/mult-low.lua
@@ -174,6 +174,8 @@ return {
         "ruledhglue", "ruledvglue", "normalhglue", "normalvglue",
         "ruledpenalty",
         --
+        "filledhboxb", "filledhboxr", "filledhboxg", "filledhboxc", "filledhboxm", "filledhboxy", "filledhboxk",
+        --
         "scratchcounter", "globalscratchcounter",
         "scratchdimen", "globalscratchdimen",
         "scratchskip", "globalscratchskip",
@@ -198,6 +200,7 @@ return {
         "scratchtoksone", "scratchtokstwo", "scratchtoksthree",
         "scratchboxone", "scratchboxtwo", "scratchboxthree",
         "scratchnx", "scratchny", "scratchmx", "scratchmy",
+        "scratchunicode",
         --
         "scratchleftskip", "scratchrightskip", "scratchtopskip", "scratchbottomskip",
         --
@@ -270,6 +273,7 @@ return {
         "dosingleempty", "dodoubleempty", "dotripleempty", "doquadrupleempty", "doquintupleempty", "dosixtupleempty", "doseventupleempty",
         "dosingleargument", "dodoubleargument", "dotripleargument", "doquadrupleargument", "doquintupleargument", "dosixtupleargument", "doseventupleargument",
         "dosinglegroupempty", "dodoublegroupempty", "dotriplegroupempty", "doquadruplegroupempty", "doquintuplegroupempty",
+        "permitspacesbetweengroups", "dontpermitspacesbetweengroups",
         --
         "nopdfcompression", "maximumpdfcompression", "normalpdfcompression",
         --
diff --git a/tex/context/base/mult-nl.mkii b/tex/context/base/mult-nl.mkii
index 9247f7ebf..3e4d6ede1 100644
--- a/tex/context/base/mult-nl.mkii
+++ b/tex/context/base/mult-nl.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{hoofdstuk}
 \setinterfacevariable{character}{letter}
 \setinterfacevariable{characters}{letters}
+\setinterfacevariable{chemistry}{chemie}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{kleur}
 \setinterfacevariable{column}{kolom}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{onder}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{ondercommando}
 \setinterfaceconstant{bottomdistance}{onderafstand}
 \setinterfaceconstant{bottomframe}{onderkader}
 \setinterfaceconstant{bottomoffset}{onderoffset}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{menu}
 \setinterfaceconstant{method}{methode}
 \setinterfaceconstant{middle}{midden}
+\setinterfaceconstant{middlecommand}{middencommando}
 \setinterfaceconstant{middlespeech}{middenuitspraak}
 \setinterfaceconstant{middletext}{middentekst}
 \setinterfaceconstant{midsentence}{middenzin}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{tolerantie}
 \setinterfaceconstant{top}{boven}
+\setinterfaceconstant{topcommand}{bovencommando}
 \setinterfaceconstant{topdistance}{bovenafstand}
 \setinterfaceconstant{topframe}{bovenkader}
 \setinterfaceconstant{topoffset}{bovenoffset}
diff --git a/tex/context/base/mult-pe.mkii b/tex/context/base/mult-pe.mkii
index 82f7abcd9..ecff40bd7 100644
--- a/tex/context/base/mult-pe.mkii
+++ b/tex/context/base/mult-pe.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{فصل}
 \setinterfacevariable{character}{حرف}
 \setinterfacevariable{characters}{حرفها}
+\setinterfacevariable{chemistry}{chemistry}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{رنگ}
 \setinterfacevariable{column}{ستون}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{پایین}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{bottomcommand}
 \setinterfaceconstant{bottomdistance}{فاصله‌پایین}
 \setinterfaceconstant{bottomframe}{قالب‌پایین}
 \setinterfaceconstant{bottomoffset}{آفست‌پایین}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{منو}
 \setinterfaceconstant{method}{روش}
 \setinterfaceconstant{middle}{میان}
+\setinterfaceconstant{middlecommand}{middlecommand}
 \setinterfaceconstant{middlespeech}{سخنرانی‌میانی}
 \setinterfaceconstant{middletext}{متن‌میانی}
 \setinterfaceconstant{midsentence}{جمله‌میانی}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{بردباری}
 \setinterfaceconstant{top}{بالا}
+\setinterfaceconstant{topcommand}{topcommand}
 \setinterfaceconstant{topdistance}{فاصله‌بالا}
 \setinterfaceconstant{topframe}{قالب‌راست}
 \setinterfaceconstant{topoffset}{آفست‌بالا}
diff --git a/tex/context/base/mult-ro.mkii b/tex/context/base/mult-ro.mkii
index 01ffe9fbe..6f4a1be86 100644
--- a/tex/context/base/mult-ro.mkii
+++ b/tex/context/base/mult-ro.mkii
@@ -120,6 +120,7 @@
 \setinterfacevariable{chapter}{capitol}
 \setinterfacevariable{character}{caracter}
 \setinterfacevariable{characters}{caractere}
+\setinterfacevariable{chemistry}{chemistry}
 \setinterfacevariable{cite}{cite}
 \setinterfacevariable{color}{culoare}
 \setinterfacevariable{column}{coloana}
@@ -594,6 +595,7 @@
 \setinterfaceconstant{bottom}{jos}
 \setinterfaceconstant{bottomafter}{bottomafter}
 \setinterfaceconstant{bottombefore}{bottombefore}
+\setinterfaceconstant{bottomcommand}{bottomcommand}
 \setinterfaceconstant{bottomdistance}{distantajos}
 \setinterfaceconstant{bottomframe}{framejos}
 \setinterfaceconstant{bottomoffset}{offsetjos}
@@ -805,6 +807,7 @@
 \setinterfaceconstant{menu}{meniu}
 \setinterfaceconstant{method}{metoda}
 \setinterfaceconstant{middle}{mijloc}
+\setinterfaceconstant{middlecommand}{middlecommand}
 \setinterfaceconstant{middlespeech}{middlespeech}
 \setinterfaceconstant{middletext}{textmijloc}
 \setinterfaceconstant{midsentence}{midsentence}
@@ -1045,6 +1048,7 @@
 \setinterfaceconstant{toffset}{toffset}
 \setinterfaceconstant{tolerance}{toleranta}
 \setinterfaceconstant{top}{sus}
+\setinterfaceconstant{topcommand}{topcommand}
 \setinterfaceconstant{topdistance}{distantasus}
 \setinterfaceconstant{topframe}{framesus}
 \setinterfaceconstant{topoffset}{offsetsus}
diff --git a/tex/context/base/node-bck.lua b/tex/context/base/node-bck.lua
index 35fdd3a36..2630df2f4 100644
--- a/tex/context/base/node-bck.lua
+++ b/tex/context/base/node-bck.lua
@@ -73,8 +73,10 @@ local function add_backgrounds(head) -- rather old code .. to be redone
                         end
                         rule.next = glue
                         glue.prev = rule
-                        glue.next = list
-                        list.prev = glue
+                        if list then
+                            glue.next = list
+                            list.prev = glue
+                        end
                         current.list = rule
                     end
                 end
@@ -132,8 +134,10 @@ local function add_alignbackgrounds(head)
                             end
                             rule.next = glue
                             glue.prev = rule
-                            glue.next = list
-                            list.prev = glue
+                            if list then
+                                glue.next = list
+                                list.prev = glue
+                            end
                             current.list = rule
                         end
                     end
diff --git a/tex/context/base/spac-ver.mkiv b/tex/context/base/spac-ver.mkiv
index 0b280c149..f407a66d8 100644
--- a/tex/context/base/spac-ver.mkiv
+++ b/tex/context/base/spac-ver.mkiv
@@ -972,6 +972,14 @@
   {\def\strutwidth{.8pt}%
    \setstrut}
 
+\unexpanded\def\dontshowstruts
+  {\unsetteststrut
+   \settestcrlf}
+
+\unexpanded\def\unsetteststrut
+  {\let\strutwidth\zeropoint
+   \setstrut}
+
 \def\autostrutfactor{1.1}
 
 \unexpanded\def\setautostrut
diff --git a/tex/context/base/status-files.pdf b/tex/context/base/status-files.pdf
index 7f3f8b150..dd73b2e66 100644
--- a/tex/context/base/status-files.pdf
+++ b/tex/context/base/status-files.pdf
diff --git a/tex/context/base/status-lua.pdf b/tex/context/base/status-lua.pdf
index f59856803..c1712b6b2 100644
--- a/tex/context/base/status-lua.pdf
+++ b/tex/context/base/status-lua.pdf
diff --git a/tex/context/base/strc-lst.lua b/tex/context/base/strc-lst.lua
index 115b58063..578c0adeb 100644
--- a/tex/context/base/strc-lst.lua
+++ b/tex/context/base/strc-lst.lua
@@ -239,10 +239,10 @@ local function filtercollected(names, criterium, number, collected, forced, nest
     criterium = gsub(criterium or ""," ","") -- not needed
     -- new, will be applied stepwise
     local wantedblock, wantedcriterium = lpegmatch(splitter,criterium) -- block:criterium
-    if not wantedcriterium then
-        block = documents.data.block
-    elseif wantedblock == "" or wantedblock == variables.all or wantedblock == variables.text then
+    if wantedblock == "" or wantedblock == variables.all or wantedblock == variables.text then
         criterium = wantedcriterium ~= "" and wantedcriterium or criterium
+    elseif not wantedcriterium then
+        block = documents.data.block
     else
         block, criterium = wantedblock, wantedcriterium
     end
diff --git a/tex/context/base/strc-ref.lua b/tex/context/base/strc-ref.lua
index 0fd8fcd93..e5ce5973b 100644
--- a/tex/context/base/strc-ref.lua
+++ b/tex/context/base/strc-ref.lua
@@ -1858,13 +1858,19 @@ filters.section = { }
 function filters.section.number(data,what,prefixspec)
     if data then
         local numberdata = data.numberdata
-        if numberdata then
-            sections.typesetnumber(numberdata,"number",prefixspec,numberdata)
-        else
+        if not numberdata then
             local useddata = data.useddata
             if useddata and useddata.number then
                 context(useddata.number)
             end
+        elseif numberdata.hidenumber then
+            local references = data.references
+            if references then
+                report_unknown("reference %q has a hidden number",references.reference or "?")
+            end
+            context.wrongreference() -- maybe an option
+        else
+            sections.typesetnumber(numberdata,"number",prefixspec,numberdata)
         end
     end
 end
diff --git a/tex/context/base/strc-ref.mkvi b/tex/context/base/strc-ref.mkvi
index edbeded68..e69df8d7b 100644
--- a/tex/context/base/strc-ref.mkvi
+++ b/tex/context/base/strc-ref.mkvi
@@ -603,6 +603,7 @@
 %D text).
 
 \def\dummyreference{{\tttf ??}}
+\def\wrongreference{{\tttf !!}}
 
 %D To prevent repetitive messages concerning a reference
 %D being defined, we set such an unknown reference to an empty
diff --git a/tex/context/base/syst-aux.mkiv b/tex/context/base/syst-aux.mkiv
index 058a251cb..406bbae8b 100644
--- a/tex/context/base/syst-aux.mkiv
+++ b/tex/context/base/syst-aux.mkiv
@@ -2712,8 +2712,8 @@
 
 \newconditional\c_syst_helpers_permit_spaces_between_groups
 
-\def    \permitspacesbetweengroups{\settrue \c_syst_helpers_permit_spaces_between_groups}
-\def\dontpermitspacesbetweengroups{\setfalse\c_syst_helpers_permit_spaces_between_groups}
+\unexpanded\def    \permitspacesbetweengroups{\settrue \c_syst_helpers_permit_spaces_between_groups}
+\unexpanded\def\dontpermitspacesbetweengroups{\setfalse\c_syst_helpers_permit_spaces_between_groups}
 
 \dontpermitspacesbetweengroups
 
diff --git a/tex/context/base/syst-ini.mkiv b/tex/context/base/syst-ini.mkiv
index 1c87c4ed4..59313ba49 100644
--- a/tex/context/base/syst-ini.mkiv
+++ b/tex/context/base/syst-ini.mkiv
@@ -364,6 +364,8 @@
 \newcount\scratchmx
 \newcount\scratchmy
 
+\newcount\scratchunicode
+
 \newdimen\scratchleftskip
 \newdimen\scratchrightskip
 \newdimen\scratchtopskip
diff --git a/tex/context/base/trac-vis.mkiv b/tex/context/base/trac-vis.mkiv
index 2ec48f375..99269c6dc 100644
--- a/tex/context/base/trac-vis.mkiv
+++ b/tex/context/base/trac-vis.mkiv
@@ -89,7 +89,7 @@
 \definecolor[f:c:t][a=1,t=.25,c=1]
 \definecolor[f:m:t][a=1,t=.25,m=1]
 \definecolor[f:y:t][a=1,t=.25,y=1]
-\definecolor[f:k:t][a=1,t=.25,k=1]
+\definecolor[f:k:t][a=1,t=.25,s=0]
 
 % \def\node_backgrounds_boxes_add#1[#2]%
 %   {\node_backgrounds_boxes_initialize
diff --git a/tex/context/interface/keys-cs.xml b/tex/context/interface/keys-cs.xml
index 05c9fdf1d..a4afdd708 100644
--- a/tex/context/interface/keys-cs.xml
+++ b/tex/context/interface/keys-cs.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='kapitola'/>
 		<cd:variable name='character' value='pismeno'/>
 		<cd:variable name='characters' value='pismena'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='barevne'/>
 		<cd:variable name='column' value='column'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='spodek'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='vzdalenostspodku'/>
 		<cd:constant name='bottomframe' value='ramecekdole'/>
 		<cd:constant name='bottomoffset' value='offsetspodku'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='menu'/>
 		<cd:constant name='method' value='metoda'/>
 		<cd:constant name='middle' value='stredni'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='middlespeech'/>
 		<cd:constant name='middletext' value='strednitext'/>
 		<cd:constant name='midsentence' value='midsentence'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='tolerance'/>
 		<cd:constant name='top' value='vrsek'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='vzdalenostvrsku'/>
 		<cd:constant name='topframe' value='rameceknahore'/>
 		<cd:constant name='topoffset' value='offsetvrsku'/>
diff --git a/tex/context/interface/keys-de.xml b/tex/context/interface/keys-de.xml
index 31a48c2a2..db8b98c10 100644
--- a/tex/context/interface/keys-de.xml
+++ b/tex/context/interface/keys-de.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='kapitel'/>
 		<cd:variable name='character' value='buchstabe'/>
 		<cd:variable name='characters' value='buchstaben'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='farbe'/>
 		<cd:variable name='column' value='column'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='unten'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='abstandunten'/>
 		<cd:constant name='bottomframe' value='untenrahmen'/>
 		<cd:constant name='bottomoffset' value='untenoffset'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='menue'/>
 		<cd:constant name='method' value='methode'/>
 		<cd:constant name='middle' value='mittig'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='middlespeech'/>
 		<cd:constant name='middletext' value='mittigertext'/>
 		<cd:constant name='midsentence' value='midsentence'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='toleranz'/>
 		<cd:constant name='top' value='oben'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='obenabstand'/>
 		<cd:constant name='topframe' value='obenrahmen'/>
 		<cd:constant name='topoffset' value='obenoffset'/>
diff --git a/tex/context/interface/keys-en.xml b/tex/context/interface/keys-en.xml
index 57475e65b..ea8596926 100644
--- a/tex/context/interface/keys-en.xml
+++ b/tex/context/interface/keys-en.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='chapter'/>
 		<cd:variable name='character' value='character'/>
 		<cd:variable name='characters' value='characters'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='color'/>
 		<cd:variable name='column' value='column'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='bottom'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='bottomdistance'/>
 		<cd:constant name='bottomframe' value='bottomframe'/>
 		<cd:constant name='bottomoffset' value='bottomoffset'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='menu'/>
 		<cd:constant name='method' value='method'/>
 		<cd:constant name='middle' value='middle'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='middlespeech'/>
 		<cd:constant name='middletext' value='middletext'/>
 		<cd:constant name='midsentence' value='midsentence'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='tolerance'/>
 		<cd:constant name='top' value='top'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='topdistance'/>
 		<cd:constant name='topframe' value='topframe'/>
 		<cd:constant name='topoffset' value='topoffset'/>
diff --git a/tex/context/interface/keys-fr.xml b/tex/context/interface/keys-fr.xml
index 7fb90a042..13a6924bd 100644
--- a/tex/context/interface/keys-fr.xml
+++ b/tex/context/interface/keys-fr.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='chapitre'/>
 		<cd:variable name='character' value='caractere'/>
 		<cd:variable name='characters' value='caracteres'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='couleur'/>
 		<cd:variable name='column' value='colonne'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='inf'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='distanceinf'/>
 		<cd:constant name='bottomframe' value='cadreinf'/>
 		<cd:constant name='bottomoffset' value='decalageinf'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='menu'/>
 		<cd:constant name='method' value='methode'/>
 		<cd:constant name='middle' value='milieu'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='middlespeech'/>
 		<cd:constant name='middletext' value='textecentre'/>
 		<cd:constant name='midsentence' value='midsentence'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='tolerance'/>
 		<cd:constant name='top' value='sup'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='distancesup'/>
 		<cd:constant name='topframe' value='cadresup'/>
 		<cd:constant name='topoffset' value='decalagesup'/>
diff --git a/tex/context/interface/keys-it.xml b/tex/context/interface/keys-it.xml
index 336930e16..63fb0d4f3 100644
--- a/tex/context/interface/keys-it.xml
+++ b/tex/context/interface/keys-it.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='capitolo'/>
 		<cd:variable name='character' value='lettera'/>
 		<cd:variable name='characters' value='lettere'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='colore'/>
 		<cd:variable name='column' value='colonna'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='fondo'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='distanzafondo'/>
 		<cd:constant name='bottomframe' value='cornicefondo'/>
 		<cd:constant name='bottomoffset' value='offsetfondo'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='menu'/>
 		<cd:constant name='method' value='metodo'/>
 		<cd:constant name='middle' value='centro'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='middlespeech'/>
 		<cd:constant name='middletext' value='testocentro'/>
 		<cd:constant name='midsentence' value='midsentence'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='tolleranza'/>
 		<cd:constant name='top' value='cima'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='distanzacima'/>
 		<cd:constant name='topframe' value='cornicecima'/>
 		<cd:constant name='topoffset' value='offsetcima'/>
diff --git a/tex/context/interface/keys-nl.xml b/tex/context/interface/keys-nl.xml
index 4e0797424..aee1820ca 100644
--- a/tex/context/interface/keys-nl.xml
+++ b/tex/context/interface/keys-nl.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='hoofdstuk'/>
 		<cd:variable name='character' value='letter'/>
 		<cd:variable name='characters' value='letters'/>
+		<cd:variable name='chemistry' value='chemie'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='kleur'/>
 		<cd:variable name='column' value='kolom'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='onder'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='ondercommando'/>
 		<cd:constant name='bottomdistance' value='onderafstand'/>
 		<cd:constant name='bottomframe' value='onderkader'/>
 		<cd:constant name='bottomoffset' value='onderoffset'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='menu'/>
 		<cd:constant name='method' value='methode'/>
 		<cd:constant name='middle' value='midden'/>
+		<cd:constant name='middlecommand' value='middencommando'/>
 		<cd:constant name='middlespeech' value='middenuitspraak'/>
 		<cd:constant name='middletext' value='middentekst'/>
 		<cd:constant name='midsentence' value='middenzin'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='tolerantie'/>
 		<cd:constant name='top' value='boven'/>
+		<cd:constant name='topcommand' value='bovencommando'/>
 		<cd:constant name='topdistance' value='bovenafstand'/>
 		<cd:constant name='topframe' value='bovenkader'/>
 		<cd:constant name='topoffset' value='bovenoffset'/>
diff --git a/tex/context/interface/keys-pe.xml b/tex/context/interface/keys-pe.xml
index 014a138ac..0e39a6ae7 100644
--- a/tex/context/interface/keys-pe.xml
+++ b/tex/context/interface/keys-pe.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='فصل'/>
 		<cd:variable name='character' value='حرف'/>
 		<cd:variable name='characters' value='حرفها'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='رنگ'/>
 		<cd:variable name='column' value='ستون'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='پایین'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='فاصله‌پایین'/>
 		<cd:constant name='bottomframe' value='قالب‌پایین'/>
 		<cd:constant name='bottomoffset' value='آفست‌پایین'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='منو'/>
 		<cd:constant name='method' value='روش'/>
 		<cd:constant name='middle' value='میان'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='سخنرانی‌میانی'/>
 		<cd:constant name='middletext' value='متن‌میانی'/>
 		<cd:constant name='midsentence' value='جمله‌میانی'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='بردباری'/>
 		<cd:constant name='top' value='بالا'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='فاصله‌بالا'/>
 		<cd:constant name='topframe' value='قالب‌راست'/>
 		<cd:constant name='topoffset' value='آفست‌بالا'/>
diff --git a/tex/context/interface/keys-ro.xml b/tex/context/interface/keys-ro.xml
index 77209d4bb..e9ff43962 100644
--- a/tex/context/interface/keys-ro.xml
+++ b/tex/context/interface/keys-ro.xml
@@ -123,6 +123,7 @@
 		<cd:variable name='chapter' value='capitol'/>
 		<cd:variable name='character' value='caracter'/>
 		<cd:variable name='characters' value='caractere'/>
+		<cd:variable name='chemistry' value='chemistry'/>
 		<cd:variable name='cite' value='cite'/>
 		<cd:variable name='color' value='culoare'/>
 		<cd:variable name='column' value='coloana'/>
@@ -600,6 +601,7 @@
 		<cd:constant name='bottom' value='jos'/>
 		<cd:constant name='bottomafter' value='bottomafter'/>
 		<cd:constant name='bottombefore' value='bottombefore'/>
+		<cd:constant name='bottomcommand' value='bottomcommand'/>
 		<cd:constant name='bottomdistance' value='distantajos'/>
 		<cd:constant name='bottomframe' value='framejos'/>
 		<cd:constant name='bottomoffset' value='offsetjos'/>
@@ -811,6 +813,7 @@
 		<cd:constant name='menu' value='meniu'/>
 		<cd:constant name='method' value='metoda'/>
 		<cd:constant name='middle' value='mijloc'/>
+		<cd:constant name='middlecommand' value='middlecommand'/>
 		<cd:constant name='middlespeech' value='middlespeech'/>
 		<cd:constant name='middletext' value='textmijloc'/>
 		<cd:constant name='midsentence' value='midsentence'/>
@@ -1051,6 +1054,7 @@
 		<cd:constant name='toffset' value='toffset'/>
 		<cd:constant name='tolerance' value='toleranta'/>
 		<cd:constant name='top' value='sus'/>
+		<cd:constant name='topcommand' value='topcommand'/>
 		<cd:constant name='topdistance' value='distantasus'/>
 		<cd:constant name='topframe' value='framesus'/>
 		<cd:constant name='topoffset' value='offsetsus'/>
diff --git a/tex/generic/context/luatex/luatex-fonts-merged.lua b/tex/generic/context/luatex/luatex-fonts-merged.lua
index 000b7fae9..2e455b3f2 100644
--- a/tex/generic/context/luatex/luatex-fonts-merged.lua
+++ b/tex/generic/context/luatex/luatex-fonts-merged.lua
@@ -1,6 +1,6 @@
 -- merged file : luatex-fonts-merged.lua
 -- parent file : luatex-fonts.lua
--- merge date  : 01/02/13 18:19:13
+-- merge date  : 01/07/13 23:25:28
 
 do -- begin closure to overcome local limits and interference
 
@@ -5710,7 +5710,7 @@ local otf                = fonts.handlers.otf
 
 otf.glists               = { "gsub", "gpos" }
 
-otf.version              = 2.737 -- beware: also sync font-mis.lua
+otf.version              = 2.738 -- beware: also sync font-mis.lua
 otf.cache                = containers.define("fonts", "otf", otf.version, true)
 
 local fontdata           = fonts.hashes.identifiers