beta 2011.10.12 19:30

6 files changed, 379 insertions, 2043 deletions

diff --git a/metapost/context/base/metafun.mpii b/metapost/context/base/metafun.mpii
index 705900a18..65d7b87f8 100644
--- a/metapost/context/base/metafun.mpii
+++ b/metapost/context/base/metafun.mpii
@@ -37,8 +37,8 @@ input mp-text.mp ;
 input mp-txts.mp ;
 input mp-shap.mp ;
 input mp-butt.mp ;
-input mp-char.mp ;
-input mp-step.mp ;
+input mp-char.mpii ;
+input mp-step.mpii ;
 input mp-grph.mp ;
 input mp-figs.mp ;
 input mp-grid.mp ;
diff --git a/metapost/context/base/metafun.mpiv b/metapost/context/base/metafun.mpiv
index 80cfcd423..b32e301a7 100644
--- a/metapost/context/base/metafun.mpiv
+++ b/metapost/context/base/metafun.mpiv
@@ -24,8 +24,8 @@ input mp-text.mp   ;
 input mp-txts.mp   ;
 input mp-butt.mp   ;
 input mp-shap.mp   ;
-%     mp-char.mp   ; % there no need to always load this
-%     mp-step.mp   ; % there no need to always load this
+%     mp-char.mpiv ; % there no need to always load this
+%     mp-step.mpiv ; % there no need to always load this
 input mp-grph.mp   ;
 input mp-figs.mp   ;
 input mp-mlib.mpiv ;
diff --git a/metapost/context/base/mp-char.mp b/metapost/context/base/mp-char.mp
deleted file mode 100644
index 3a7a1d939..000000000
--- a/metapost/context/base/mp-char.mp
+++ /dev/null
@@ -1,1019 +0,0 @@
-% to be cleaned up, namespace needed ! ! ! ! !
-
-%D \module
-%D   [       file=mp-char.mp,
-%D        version=1998.10.10,
-%D          title=\CONTEXT\ \METAPOST\ graphics,
-%D       subtitle=charts,
-%D         author=Hans Hagen,
-%D           date=\currentdate,
-%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
-%C
-%C This module is part of the \CONTEXT\ macro||package and is
-%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
-%C details.
-
-if unknown context_tool :    input mp-tool ; fi ;
-if unknown context_shap :    input mp-shap ; fi ;
-if   known context_char : endinput         ; fi ;
-
-boolean context_char ; context_char := true ;
-
-% kan naar elders
-
-current_position := 0 ;
-
-def save_text_position (expr p) =  % beware: clip shift needed
-  current_position := current_position + 1 ;
-  savedata
-    "\MPposition{" & decimal current_position & "}{"
-                   & decimal xpart p          & "}{"
-                   & decimal ypart p          & "}%" ;
-enddef ;
-
-%D settings
-
-grid_width   := 60pt ; grid_height  := 40pt ;
-shape_width  := 45pt ; shape_height := 30pt ;
-
-chart_offset :=  2pt ;
-color chart_background_color ; chart_background_color := white ;
-
-%D test mode
-
-boolean show_mid_points ; show_mid_points := false ;
-boolean show_con_points ; show_con_points := false ;
-boolean show_all_points ; show_all_points := false ;
-
-%D shapes
-
-color shape_line_color, shape_fill_color ;
-
-shape_line_width := 2pt ;
-shape_line_color := .5white ;
-shape_fill_color := .9white ;
-
-shape_node           :=  0 ;
-shape_action         := 24 ;
-shape_procedure      :=  5 ;
-shape_product        := 12 ;
-shape_decision       := 14 ;
-shape_archive        := 19 ;
-shape_loop           := 35 ;
-shape_wait           :=  6 ;
-shape_subprocedure   := 20 ; shape_sub_procedure   := 20 ;
-shape_singledocument := 32 ; shape_single_document := 32 ;
-shape_multidocument  := 33 ; shape_multi_document  := 33 ;
-shape_right          := 66 ;
-shape_left           := 67 ;
-shape_up             := 68 ;
-shape_down           := 69 ;
-
-% vardef some_shape_path (expr type) == imported from mp-shap
-
-def show_shapes (expr n) =
-
-  begin_chart(n,8,10) ;
-    show_con_points := true ;
-    for i=0 upto 7 :
-      for j=0 upto 9 :
-        new_shape(i+1,j+1,i*10+j);
-      endfor ;
-    endfor ;
-  end_chart ;
-
-enddef ;
-
-%D connections
-
-def new_chart =
-
-  color connection_line_color ;
-
-  connection_line_width  := shape_line_width ;
-  connection_line_color  := .8white ;
-  connection_smooth_size := 5pt ;
-  connection_arrow_size  := 4pt ;
-  connection_dash_size   := 3pt ;
-
-  max_x := 6 ;
-  max_y := 4 ;
-
-  numeric xypoint       ; xypoint := 0 ;
-
-  pair    xypoints []   ;
-
-  boolean xyfree   [][] ;
-  path    xypath   [][] ;
-  numeric xysx     [][] ;
-  numeric xysy     [][] ;
-  color   xyfill   [][] ;
-  color   xydraw   [][] ;
-  numeric xyline   [][] ;
-  boolean xypeep   [][] ;
-  picture xypicture[][] ;
-
-  numeric cpath         ; cpath := 0 ;
-  path    cpaths    []  ;
-  numeric cline     []  ;
-  color   ccolor    []  ;
-  boolean carrow    []  ;
-  boolean cdash     []  ;
-  boolean ccross    []  ;
-
-  boolean smooth        ; smooth       := true  ;
-  boolean peepshape     ; peepshape    := false ;
-  boolean arrowtip      ; arrowtip     := true  ;
-  boolean dashline      ; dashline     := false ;
-  boolean forcevalid    ; forcevalid   := false ;
-  boolean touchshape    ; touchshape   := false ;
-  boolean showcrossing  ; showcrossing := false ;
-
-  picture dash_pattern ;
-
-  boolean reverse_y ; reverse_y := true ;
-
-enddef ;
-
-new_chart ;
-
-def y_pos (expr y) =
-  if reverse_y : max_y + 1 - y else : y fi
-enddef ;
-
-def initialize_grid (expr maxx, maxy) =
-  begingroup ;
-  save i, j ;
-  max_x := maxx ;
-  max_y := maxy ;
-  dsp_x := 0 ;
-  dsp_y := 0 ;
-  for x=1 upto max_x :
-    for y=1 upto max_y :
-      xyfree [x][y] := true ;
-      xyfill [x][y] := shape_fill_color ;
-      xydraw [x][y] := shape_line_color ;
-      xyline [x][y] := shape_line_width ;
-    endfor ;
-  endfor ;
-  endgroup ;
-enddef ;
-
-def scaled_to_grid =
-  xscaled grid_width yscaled grid_height
-enddef ;
-
-def xy_offset (expr x, y) =
-  (x+.5,y+.5)
-enddef ;
-
-def draw_shape (expr x, yy, p, sx, sy) =
-  begingroup ;
-  save y ;
-  y := y_pos(yy) ;
-  xypath [x][y] := (p xscaled sx yscaled sy) shifted xy_offset(x,y) ;
-  xyfree [x][y] := false ;
-  xysx   [x][y] := sx ;
-  xysy   [x][y] := sy ;
-  xyfill [x][y] := shape_fill_color ;
-  xydraw [x][y] := shape_line_color ;
-  xyline [x][y] := shape_line_width ;
-  xypeep [x][y] := peepshape ;
-  endgroup ;
-enddef ;
-
-vardef i_point (expr x, y, p, t) =
-  begingroup ;
-  save q, ok ;
-  pair q ;
-  boolean ok ;
-  q := xypath[x][y] intersection_point ((p) shifted xy_offset(x,y)) ;
-  ok := true ;
-%  if xpart q < -.5 : ok := false ; q := (-.45,ypart q) fi ;
-%  if xpart q >  .5 : ok := false ; q := ( .45,ypart q) fi ;
-%  if ypart q < -.5 : ok := false ; q := (xpart q,-.45) fi ;
-%  if ypart q >  .5 : ok := false ; q := (xpart q, .45) fi ;
-  if not ok :
-    message (t & " of shape (" & decimal x & "," & decimal y & ") limited") ;
-  fi ;
-  q
-  endgroup
-enddef ;
-
-vardef trimmed (expr x, y, z, t) =
-  if touchshape and t : xyline[x][y]/z else : epsilon fi
-enddef ;
-
-zfactor := 1/3 ;
-
-vardef xy_bottom (expr x, y, z, t) =
-  i_point (x, y, ((0,0)--(0,-2)) shifted (zfactor*z*xysx[x][y],0), "bottom")
-  shifted(0,-trimmed(x,y,grid_height,t))
-enddef ;
-
-vardef xy_top (expr x, y, z, t) =
-  i_point (x, y, ((0,0)--(0,2))  shifted (zfactor*z*xysx[x][y],0), "top")
-  shifted(0,trimmed(x,y,grid_height,t))
-enddef ;
-
-vardef xy_left (expr x, y, z, t) =
-  i_point (x, y, ((0,0)--(-2,0)) shifted (0,zfactor*z*xysy[x][y]), "left")
-  shifted(-trimmed(x,y,grid_width,t),0)
-enddef ;
-
-vardef xy_right (expr x, y, z, t) =
-  i_point (x, y, ((0,0)--(2,0))  shifted (0,zfactor*z*xysy[x][y]), "right")
-  shifted(trimmed(x,y,grid_width,t),0)
-enddef ;
-
-def flush_shapes =
-  for x=1 upto max_x :
-    for y=1 upto max_y :
-      flush_shape (x, y) ;
-    endfor ;
-  endfor ;
-enddef ;
-
-def flush_pictures =
-  for x=1 upto max_x :
-    for y=1 upto max_y :
-      flush_picture (x, y) ;
-    endfor ;
-  endfor ;
-enddef ;
-
-
-def draw_connection_point (expr x, y, z) =
-  pickup pencircle scaled if (z=0): 2 fi xyline[x][y] ;
-  drawdot xy_bottom(x,y,z,false) scaled_to_grid withcolor (1,0,0) ;
-  drawdot xy_top   (x,y,z,false) scaled_to_grid withcolor (0,1,0) ;
-  drawdot xy_left  (x,y,z,false) scaled_to_grid withcolor (0,0,1) ;
-  drawdot xy_right (x,y,z,false) scaled_to_grid withcolor (1,1,0) ;
-enddef ;
-
-def flush_shape (expr x, yy) =
-  begingroup ;
-  save y ;
-  y := y_pos(yy) ;
-  if not xyfree[x][y] :
-    pickup pencircle scaled xyline[x][y] ;
-    if xypeep[x][y] :
-      fill (xypath[x][y] peepholed (unitsquare shifted (x,y)))
-        scaled_to_grid withpen pencircle scaled 0
-        withcolor chart_background_color ;
-    else :
-      fill xypath[x][y] scaled_to_grid withcolor xyfill[x][y] ;
-    fi ;
-    draw xypath[x][y] scaled_to_grid withcolor xydraw[x][y] ;
-    if show_con_points or show_all_points :
-      draw_connection_point (x, y, 0) ;
-    fi ;
-    if show_all_points :
-      for i=-1 upto 1 :
-        draw_connection_point (x, y, i) ;
-      endfor ;
-    fi ;
-  fi ;
-  endgroup ;
-enddef ;
-
-vardef points_initialized (expr xfrom, yfrom, xto, yto, n) =
-  if not xyfree[xfrom][yfrom] and not xyfree[xto][yto] :
-    xypoint := n ; true
-  else :
-    xypoint := 0 ; false
-  fi
-enddef ;
-
-def collapse_points = % this is now an mp-tool macro
-  % remove redundant points
-  n := 1 ;
-  for i=2 upto xypoint:
-    if not (xypoints[i]=xypoints[n]) :
-      n := n + 1 ;
-      xypoints[n] := xypoints[i]
-    fi ;
-  endfor ;
-  xypoint := n ;
-  % make straight lines
-  if xypoints[2]=xypoints[xypoint-1] :
-    xypoints[3] := xypoints[xypoint] ;
-    xypoint := 3 ;
-  fi ;
-enddef ;
-
-vardef smooth_connection (expr a,b) =
-  sx := connection_smooth_size/grid_width ;
-  sy := connection_smooth_size/grid_height ;
-  if ypart a = ypart b :
-    a shifted (if xpart a >= xpart b : - fi sx,0)
-% a shifted (sx*xpart unitvector(b-a),0)
-  else :
-    a shifted (0,if ypart a >= ypart b : - fi sy)
-% a shifted (0,sy*ypart unitvector(b-a))
-  fi
-enddef ;
-
-vardef trim_points =
-  begingroup
-  save p, a, b, d, i ; path p ; pair d ;
-  p := for i=1 upto xypoint-1 : xypoints[i]-- endfor xypoints[xypoint] ;
-  if touchshape :
-    a := shape_line_width/grid_width ;
-    b := shape_line_width/grid_height ;
-  else :
-    a := epsilon ;
-    b := epsilon ;
-  fi ;
-  d := direction infinity of p ;
-  xypoints[xypoint] := xypoints[xypoint] shifted
-  if     xpart d < 0 : (+a,0) ;
-  elseif xpart d > 0 : (-a,0) ;
-  elseif ypart d < 0 : (0,+b) ;
-  elseif ypart d > 0 : (0,-b) ;
-  else               : origin ;
-  fi ;
-  d := direction 0 of p ;
-  xypoints[1] := xypoints[1] shifted
-  if     xpart d < 0 : (-a,0) ;
-  elseif xpart d > 0 : (+a,0) ;
-  elseif ypart d < 0 : (0,-b) ;
-  elseif ypart d > 0 : (0,+b) ;
-  else               : origin ;
-  fi ;
-  endgroup
-enddef ;
-
-vardef trim_points = enddef ;
-
-vardef connection_path =
-  if reverse_connection : reverse fi (xypoints[1]--
-  for i=2 upto xypoint-1 :
-    if smooth :
-      smooth_connection(xypoints[i],xypoints[i-1])  ..
-      controls xypoints[i] and xypoints[i] ..
-      smooth_connection(xypoints[i],xypoints[i+1])  --
-    else :
-      xypoints[i]--
-    fi
-  endfor
-  xypoints[xypoint])
-enddef ;
-
-% vardef connection_path =
-%   sx := connection_smooth_size/grid_width ;
-%   sy := connection_smooth_size/grid_height ;
-%   if reverse_connection : reverse fi
-%   (for i=1 upto xypoint-1 : xypoints[i] -- endfor xypoints[xypoint])
-%   if smooth : cornered max(sx,sy) fi
-% enddef ;
-%
-% primarydef p cornered c =
-%   if cycle p :
-%     ((point 0 of p) shifted (c*(unitvector(point 1 of p - point 0 of p))) --
-%      for i=1 upto length(p) :
-%        (point i-1 of p) shifted (c*(unitvector(point i   of p - point i-1 of p))) --
-%        (point i   of p) shifted (c*(unitvector(point i-1 of p - point i   of p))) ..
-%        controls point i of p ..
-%      endfor cycle)
-%   else :
-%     ((point 0 of p) --
-%      for i=1 upto length(p)-1 :
-%        (point i-1 of p) shifted (c*(unitvector(point i   of p - point i-1 of p))) --
-%        (point i   of p) shifted (c*(unitvector(point i-1 of p - point i   of p))) ..
-%        controls point i of p ..
-%      endfor
-%      (point length(p) of p))
-%   fi
-% enddef ;
-
-def draw_connection =
-  if xypoint>0 :
-    collapse_points ;
-    trim_points ;
-    cpath := cpath + 1 ;
-    cpaths[cpath] := connection_path scaled_to_grid ;
-    cline[cpath]  := connection_line_width ;
-    ccolor[cpath] := connection_line_color ;
-    carrow[cpath] := arrowtip ;
-    cdash[cpath]  := dashline ;
-    ccross[cpath] := showcrossing ;
-  else :
-    message("no connection defined") ;
-  fi ;
-  reverse_connection := false ;
-enddef ;
-
-def flush_connections =
-  pair ip ;
-  boolean crossing ;
-  ahlength     := connection_arrow_size ;
-  dash_pattern := dashpattern(on connection_dash_size off connection_dash_size ) ;
-  for i=1 upto cpath :
-    if ccross[i] :
-      crossing := false ;
-      for j=1 upto i :
-       %if not ((point infinity of cpaths[i] = point infinity of cpaths[j]) or
-       %        (point 0        of cpaths[i] = point 0        of cpaths[j])) :
-        if not  (point infinity of cpaths[i] = point infinity of cpaths[j]) :
-          ip := cpaths[i] intersection_point cpaths[j] ;
-          if intersection_found : crossing := true fi ;
-        fi ;
-      endfor ;
-      if crossing :
-        pickup pencircle scaled 2cline[i] ;
-       %draw cpaths[i] withcolor chart_background_color ;
-        path cp ; cp := cpaths[i] ;
-        cp := cp cutbefore point .05 length cp of cp ;
-        cp := cp cutafter  point .95 length cp of cp ;
-        draw cp withcolor chart_background_color ;
-      fi ;
-    fi ;
-    pickup pencircle scaled cline[i] ;
-    if carrow[i] :
-      if cdash[i] :
-        drawarrow cpaths[i] withcolor ccolor[i] dashed dash_pattern ;
-      else :
-        drawarrow cpaths[i] withcolor ccolor[i] ;
-      fi ;
-    else :
-      if cdash[i] :
-        draw cpaths[i] withcolor ccolor[i] dashed dash_pattern ;
-      else :
-        draw cpaths[i] withcolor ccolor[i] ;
-      fi ;
-    fi ;
-    draw_midpoint (i) ;
-  endfor ;
-enddef ;
-
-def draw_midpoint (expr n) =
-  begingroup
-  save p ;
-  pair p ;
-  p := point .5*length(cpaths[n]) of cpaths[n];
-  pickup pencircle scaled 2cline[n] ;
-  save_text_position (p) ;
-  if show_mid_points :
-    drawdot p withcolor .7white ;
-  fi ;
-  endgroup ;
-enddef ;
-
-def flush_picture(expr x, y) =
-    if known xypicture[x][y]:
-        draw xypicture[x][y] shifted xy_offset((x+0.5)*grid_width,(max_y-y+1.5)*grid_height) ;
-    fi ;
-enddef ;
-
-def chart_draw_picture(expr x, y, p) =
-    xypicture[x][y] := p ;
-enddef ;
-
-boolean reverse_connection ; reverse_connection := false ;
-
-vardef up_on_grid (expr n) =
-  (xpart xypoints[n],(ypart xypoints[n]+1) div 1)
-enddef ;
-
-vardef down_on_grid (expr n) =
-  (xpart xypoints[n],(ypart xypoints[n]) div 1)
-enddef ;
-
-vardef left_on_grid (expr n) =
-  ((xpart xypoints[n]) div 1, ypart xypoints[n])
-enddef ;
-
-vardef right_on_grid (expr n) =
-  ((xpart xypoints[n]+1) div 1, ypart xypoints[n])
-enddef ;
-
-vardef x_on_grid (expr n, xfrom, xto, zfrom) =
-  if (xfrom=xto) and not (zfrom=0) :
-    if (zfrom=1) : right_on_grid(2) else : left_on_grid(2) fi
-  elseif xpart xypoints[1] < xpart xypoints[6] :
-    right_on_grid(n)
-  else :
-    left_on_grid(n)
-  fi
-enddef ;
-
-vardef y_on_grid (expr n, yfrom, yto, zfrom) =
-  if (yfrom=yto) and not (zfrom=0) :
-    if (zfrom=1) : up_on_grid(2) else : down_on_grid(2) fi
-  elseif ypart xypoints[1] < ypart xypoints[6] :
-    up_on_grid(n)
-  else :
-    down_on_grid(n)
-  fi
-enddef ;
-
-vardef xy_on_grid (expr n, m) =
-  (xpart xypoints[n], ypart xypoints[m])
-enddef ;
-
-vardef down_to_grid (expr a,b) =
-  (xpart xypoints[a],
-   ypart xypoints[if ypart xypoints[a]<ypart xypoints[b]:a else:b fi])
-enddef ;
-
-vardef up_to_grid (expr a,b) =
-  (xpart xypoints[a],
-   ypart xypoints[if ypart xypoints[a]>ypart xypoints[b]:a else:b fi])
-enddef ;
-
-vardef left_to_grid (expr a,b) =
-  (xpart xypoints[if xpart xypoints[a]<xpart xypoints[b]:a else:b fi],
-   ypart xypoints[a])
-enddef ;
-
-vardef right_to_grid (expr a,b) =
-  (xpart xypoints[if xpart xypoints[a]>xpart xypoints[b]:a else:b fi],
-   ypart xypoints[a])
-enddef ;
-
-% vardef boundingboxfraction(expr p, f) =
-%   ((boundingbox p) enlarged (-f*bbwidth(p),-f*bbheight(p)))
-% enddef ;
-
-vardef valid_connection (expr xfrom, yfrom, xto, yto) =
-  begingroup ;
-  save ok, vc, pp ;
-  boolean ok ;
-  % check for slanted lines
-  ok := true ;
-  for i=1 upto xypoint-1 :
-   if not ((xpart xypoints[i]=xpart xypoints[i+1]) or
-           (ypart xypoints[i]=ypart xypoints[i+1])) : ok := false ;
-   fi ;
-  endfor ;
-  if not ok :
-   %message("slanted");
-    false
-  elseif forcevalid :
-   %message("force");
-    true
-  elseif (xfrom=xto) and (yfrom=yto) :
-   %message("self");
-    false
-  else :
-    % check for crossing shapes
-    pair vc ;
-    path pp ;
-
-    pair xyfirst, xylast ;
-    xyfirst := xypoints[1] ;
-    xylast := xypoints[xypoint] ;
-    trim_points ;
-    pp := for i=1 upto xypoint-1 : xypoints[i]-- endfor xypoints[xypoint] ;
-    xypoints[1] := xyfirst ;
-    xypoints[xypoint] := xylast ;
-
-    for i=1 upto max_x :
-      for j=1 upto max_y :                % was bug: xfrom,yto
-        if not ( ( (i,j)=(xfrom,yfrom) ) or ( (i,j)=(xto,yto) ) ) :
-          if not xyfree[i][j] :
-            vc := pp intersection_point xypath[i][j] ;
-            if intersection_found : ok := false fi ;
-          fi ;
-        fi ;
-      endfor ;
-    endfor ;
-   %if not ok: message("crossing") ; fi ;
-    ok
-  fi
-  endgroup
-enddef ;
-
-def connect_top_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,6) :
-    xypoints[1] := xy_top(xfrom,yfrom,zfrom,true) ;
-    xypoints[6] := xy_bottom(xto,yto,zto,true) ;
-    xypoints[2] := up_on_grid(1) ;
-    xypoints[5] := down_on_grid(6) ;
-    xypoints[3] := up_to_grid(2,5) ;
-    xypoints[4] := up_to_grid(2,5) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := x_on_grid(2,xfrom,xto,zfrom) ;
-      xypoints[4] := xy_on_grid(3,5) ;
-    fi ;
-    %%%% begin experiment
-    xypoints[3] := xypoints[3] shifted (dsp_x,0) ;
-    xypoints[4] := xypoints[4] shifted (dsp_x,0) ;
-    if dsp_y>0 :
-      xypoints[2] := xypoints[2] shifted (0,dsp_y) ;
-      xypoints[3] := xypoints[3] shifted (0,dsp_y) ;
-    elseif dsp_y<0 :
-      xypoints[4] := xypoints[4] shifted (0,dsp_y) ;
-      xypoints[5] := xypoints[5] shifted (0,dsp_y) ;
-    fi
-    %%%% end experiment
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_left_right (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,6) :
-    xypoints[1] := xy_left(xfrom,yfrom,zfrom,true) ;
-    xypoints[6] := xy_right(xto,yto,zto,true) ;
-    xypoints[2] := left_on_grid(1) ;
-    xypoints[5] := right_on_grid(6) ;
-    xypoints[3] := left_to_grid(2,5) ;
-    xypoints[4] := left_to_grid(2,5) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := y_on_grid(2,yfrom,yto,zfrom) ;
-      xypoints[4] := xy_on_grid(5,3) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_left_top (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,5) :
-    xypoints[1] := xy_left(xfrom,yfrom,zfrom,true) ;
-    xypoints[5] := xy_top(xto,yto,zto,true) ;
-    xypoints[2] := left_on_grid(1) ;
-    xypoints[4] := up_on_grid(5) ;
-    xypoints[3] := left_to_grid(2,5) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := xy_on_grid(2,4) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_left_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,5) :
-    xypoints[1] := xy_left(xfrom,yfrom,zfrom,true) ;
-    xypoints[5] := xy_bottom(xto,yto,zto,true) ;
-    xypoints[2] := left_on_grid(1) ;
-    xypoints[4] := down_on_grid(5) ;
-    xypoints[3] := left_to_grid(2,5) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := xy_on_grid(2,4) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_right_top (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,5) :
-    xypoints[1] := xy_right(xfrom,yfrom,zfrom,true) ;
-    xypoints[5] := xy_top(xto,yto,zto,true) ;
-    xypoints[2] := right_on_grid(1) ;
-    xypoints[4] := up_on_grid(5) ;
-    xypoints[3] := right_to_grid(2,5) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := xy_on_grid(2,4) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_right_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,5) :
-    xypoints[1] := xy_right(xfrom,yfrom,zfrom,true) ;
-    xypoints[5] := xy_bottom(xto,yto,zto,true) ;
-    xypoints[2] := right_on_grid(1) ;
-    xypoints[4] := down_on_grid(5) ;
-    xypoints[3] := right_to_grid(2,5) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := xy_on_grid(2,4) ;
-    fi ;
-    %%%% begin experiment
-    xypoints[2] := xypoints[2] shifted (dsp_x,0) ;
-    xypoints[3] := xypoints[3] shifted (dsp_x,0) ;
-    if dsp_y>0 :
-      xypoints[3] := xypoints[3] shifted (0,-dsp_y) ;
-      xypoints[4] := xypoints[4] shifted (0,-dsp_y) ;
-    elseif dsp_y<0 :
-      xypoints[3] := xypoints[3] shifted (0,dsp_y) ;
-      xypoints[4] := xypoints[4] shifted (0,dsp_y) ;
-    fi
-    %%%% end experiment
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_left_left (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,6) :
-    xypoints[1] := xy_left(xfrom,yfrom,zfrom,true) ;
-    xypoints[6] := xy_left(xto,yto,zto,true) ;
-    xypoints[2] := left_on_grid(1) ;
-    xypoints[5] := left_on_grid(6) ;
-    xypoints[3] := left_to_grid(2,5) ;
-    xypoints[4] := left_to_grid(5,2) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := y_on_grid(2,yfrom,yto,zfrom) ;
-      xypoints[4] := xy_on_grid(5,3) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_right_right (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,6) :
-    xypoints[1] := xy_right(xfrom,yfrom,zfrom,true) ;
-    xypoints[6] := xy_right(xto,yto,zto,true) ;
-    xypoints[2] := right_on_grid(1) ;
-    xypoints[5] := right_on_grid(6) ;
-    xypoints[3] := right_to_grid(2,5) ;
-    xypoints[4] := right_to_grid(5,2) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := y_on_grid(2,yfrom,yto,zfrom) ;
-      xypoints[4] := xy_on_grid(5,3) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_top_top (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,6) :
-    xypoints[1] := xy_top(xfrom,yfrom,zfrom,true) ;
-    xypoints[6] := xy_top(xto,yto,zto,true) ;
-    xypoints[2] := up_on_grid(1) ;
-    xypoints[5] := up_on_grid(6) ;
-    xypoints[3] := up_to_grid(2,5) ;
-    xypoints[4] := up_to_grid(5,2) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := x_on_grid(2,xfrom,xto,zfrom) ;
-      xypoints[4] := xy_on_grid(3,5) ;
-    fi ;
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_bottom_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-  yfrom := y_pos(yyfrom) ; yto := y_pos(yyto) ;
-  if points_initialized(xfrom,yfrom,xto,yto,6) :
-    xypoints[1] := xy_bottom(xfrom,yfrom,zfrom,true) ;
-    xypoints[6] := xy_bottom(xto,yto,zto,true) ;
-    xypoints[2] := down_on_grid(1) ;
-    xypoints[5] := down_on_grid(6) ;
-    xypoints[3] := down_to_grid(2,5) ;
-    xypoints[4] := down_to_grid(5,2) ;
-    if not valid_connection(xfrom,yfrom,xto,yto) :
-      xypoints[3] := x_on_grid(2,xfrom,xto,zfrom) ;
-      xypoints[4] := xy_on_grid(3,5) ;
-    fi ;
-    %%%% begin experiment
-    xypoints[3] := xypoints[3] shifted (dsp_x,0) ;
-    xypoints[4] := xypoints[4] shifted (dsp_x,0) ;
-    if dsp_y<0 :
-      xypoints[2] := xypoints[2] shifted (0,-dsp_y) ;
-      xypoints[3] := xypoints[3] shifted (0,-dsp_y) ;
-    elseif dsp_y>0 :
-      xypoints[4] := xypoints[4] shifted (0,dsp_y) ;
-      xypoints[5] := xypoints[5] shifted (0,dsp_y) ;
-    fi
-    %%%% end experiment
-    draw_connection ;
-  fi ;
-enddef ;
-
-def connect_bottom_top (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-  reverse_connection := true ;
-  connect_top_bottom (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def connect_right_left (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-  reverse_connection := true ;
-  connect_left_right (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def connect_top_left (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-  reverse_connection := true ;
-  connect_left_top (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def connect_bottom_left (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-  reverse_connection := true ;
-  connect_left_bottom (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def connect_top_right (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-  reverse_connection := true ;
-  connect_right_top (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def connect_bottom_right (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-  reverse_connection := true ;
-  connect_right_bottom (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def draw_test_shape (expr x, y) =
-  draw_shape(x,y,fullcircle, .7, .7) ;
-enddef ;
-
-def draw_test_shapes =
-  for i=1 upto max_x :
-    for j=1 upto max_y :
-      draw_test_shape(i,j) ;
-    endfor ;
-  endfor ;
-enddef;
-
-def draw_test_area =
-  pickup pencircle scaled .5shape_line_width ;
-  draw (unitsquare xscaled max_x yscaled max_y shifted (1,1))
-    scaled_to_grid withcolor blue ;
-enddef ;
-
-def show_connection (expr n, m) =
-
-  begin_chart(100+n,6,6) ;
-
-    draw_test_area ;
-
-    smooth   := true ;
-    arrowtip := true ;
-    dashline := true ;
-
-    draw_test_shape(2,2) ; draw_test_shape(4,5) ;
-    draw_test_shape(3,3) ; draw_test_shape(5,1) ;
-    draw_test_shape(2,5) ; draw_test_shape(1,3) ;
-    draw_test_shape(6,2) ; draw_test_shape(4,6) ;
-
-    if     (m=1) :
-      connect_top_bottom (2,2,0) (4,5,0) ;
-      connect_top_bottom (3,3,0) (5,1,0) ;
-      connect_top_bottom (2,5,0) (1,3,0) ;
-      connect_top_bottom (6,2,0) (4,6,0) ;
-    elseif (m=2) :
-      connect_top_top (2,2,0) (4,5,0) ;
-      connect_top_top (3,3,0) (5,1,0) ;
-      connect_top_top (2,5,0) (1,3,0) ;
-      connect_top_top (6,2,0) (4,6,0) ;
-    elseif (m=3) :
-      connect_bottom_bottom (2,2,0) (4,5,0) ;
-      connect_bottom_bottom (3,3,0) (5,1,0) ;
-      connect_bottom_bottom (2,5,0) (1,3,0) ;
-      connect_bottom_bottom (6,2,0) (4,6,0) ;
-    elseif (m=4) :
-      connect_left_right (2,2,0) (4,5,0) ;
-      connect_left_right (3,3,0) (5,1,0) ;
-      connect_left_right (2,5,0) (1,3,0) ;
-      connect_left_right (6,2,0) (4,6,0) ;
-    elseif (m=5) :
-      connect_left_left (2,2,0) (4,5,0) ;
-      connect_left_left (3,3,0) (5,1,0) ;
-      connect_left_left (2,5,0) (1,3,0) ;
-      connect_left_left (6,2,0) (4,6,0) ;
-    elseif (m=6) :
-      connect_right_right (2,2,0) (4,5,0) ;
-      connect_right_right (3,3,0) (5,1,0) ;
-      connect_right_right (2,5,0) (1,3,0) ;
-      connect_right_right (6,2,0) (4,6,0) ;
-    elseif (m=7) :
-      connect_left_top (2,2,0) (4,5,0) ;
-      connect_left_top (3,3,0) (5,1,0) ;
-      connect_left_top (2,5,0) (1,3,0) ;
-      connect_left_top (6,2,0) (4,6,0) ;
-    elseif (m=8) :
-      connect_left_bottom (2,2,0) (4,5,0) ;
-      connect_left_bottom (3,3,0) (5,1,0) ;
-      connect_left_bottom (2,5,0) (1,3,0) ;
-      connect_left_bottom (6,2,0) (4,6,0) ;
-    elseif (m=9) :
-      connect_right_top (2,2,0) (4,5,0) ;
-      connect_right_top (3,3,0) (5,1,0) ;
-      connect_right_top (2,5,0) (1,3,0) ;
-      connect_right_top (6,2,0) (4,6,0) ;
-    else :
-      connect_right_bottom (2,2,0) (4,5,0) ;
-      connect_right_bottom (3,3,0) (5,1,0) ;
-      connect_right_bottom (2,5,0) (1,3,0) ;
-      connect_right_bottom (6,2,0) (4,6,0) ;
-    fi ;
-
-  end_chart ;
-
-enddef ;
-
-def show_connections =
-  for f=1 upto 10 :
-    show_connection(f,f) ;
-  endfor ;
-enddef ;
-
-%D charts
-
-def clip_chart (expr minx, miny, maxx, maxy) =
-  cmin_x := minx ;
-  cmax_x := maxx ;
-  cmin_y := miny ;
-  cmax_y := maxy ;
-enddef ;
-
-def begin_chart (expr n, maxx, maxy) =
-  new_chart ;
-  chart_figure := n ;
-  chart_scale := 1 ;
-  if chart_figure>0: beginfig(chart_figure) ; fi ;
-  startsavingdata ;
-  initialize_grid (maxx, maxy) ;
-  bboxmargin := 0 ;
-  cmin_x := 1 ;
-  cmax_x := maxx ;
-  cmin_y := 1 ;
-  cmax_y := maxy ;
-enddef ;
-
-def end_chart =
-  flush_shapes ;
-  flush_connections ;
-  flush_pictures ;
-  cmin_x := cmin_x ;
-  cmax_x := cmin_x+cmax_x ;
-  cmin_y := cmin_y-1 ;
-  cmax_y := cmin_y+cmax_y ;
-  if reverse_y :
-   cmin_y := y_pos(cmin_y) ;
-   cmax_y := y_pos(cmax_y) ;
-  fi ;
-  path p ;
-  p := (((cmin_x,cmin_y)--(cmax_x,cmin_y)--
-         (cmax_x,cmax_y)--(cmin_x,cmax_y)--cycle))
-       scaled_to_grid ;
- %draw p withcolor red ;
-  p := p enlarged chart_offset ;
-  clip currentpicture to p ;
-  setbounds currentpicture to p ;
-  savedata
-    "\MPclippath{" &
-    decimal xpart llcorner p & "}{" &
-    decimal ypart llcorner p & "}{" &
-    decimal xpart urcorner p & "}{" &
-    decimal ypart urcorner p & "}%" ;
-  savedata
-    "\MPareapath{" &
-    decimal (xpart llcorner p + 2chart_offset) & "}{" &
-    decimal (ypart llcorner p + 2chart_offset) & "}{" &
-    decimal (xpart urcorner p - 2chart_offset) & "}{" &
-    decimal (ypart urcorner p - 2chart_offset) & "}%" ;
-  currentpicture := currentpicture scaled chart_scale ;
-  stopsavingdata ;
-  if chart_figure>0: endfig ; fi ;
-enddef ;
-
-def new_shape (expr x, y, n) =
-  if known n :
-    if (x>0) and (x<=max_x) and (y>0) and (y<=max_y) :
-      sx := shape_width/grid_width ;
-      sy := shape_height/grid_height ;
-      draw_shape(x,y,some_shape_path(n), sx, sy) ;
-    else :
-      message ("shape outside grid ignored") ;
-    fi ;
-  else
-    message ("shape not known" ) ;
-  fi ;
-enddef ;
-
-def begin_sub_chart =
-  begingroup ;
-  save    shape_line_width , connection_line_width ;
-  save    shape_line_color, shape_fill_color, connection_line_color ;
-  color   shape_line_color, shape_fill_color, connection_line_color ;
-  save    smooth, arrowtip, dashline, peepshape ;
-  boolean smooth, arrowtip, dashline, peepshape ;
-enddef ;
-
-def end_sub_chart =
-  endgroup ;
-enddef ;
-
-%D done
-
-endinput ;
-
-%D testing
-
-show_shapes(100) ;
-
-end
-
-%D more testing
-
-show_connections ;
-
-begin_chart (1,4,5) ;
- %clip_chart(1,1,1,2) ;
-  new_shape (1,1,31) ;
-  new_shape (1,2,3) ;
-  new_shape (4,4,5) ;
-  connect_top_left   (1,1,0) (4,4,0) ;
-  connect_bottom_top (1,2,0) (4,4,0) ;
-  connect_left_right (1,2,0) (1,1,0) ;
-end_chart ;
-
-end
diff --git a/metapost/context/base/mp-flow.mpiv b/metapost/context/base/mp-flow.mpiv
deleted file mode 100644
index 4cf4af0f9..000000000
--- a/metapost/context/base/mp-flow.mpiv
+++ /dev/null
@@ -1,1020 +0,0 @@
-%D \module
-%D   [       file=mp-char.mp,
-%D        version=2011.10.1, % 1998.10.10,
-%D          title=\CONTEXT\ \METAPOST\ graphics,
-%D       subtitle=charts,
-%D         author=Hans Hagen,
-%D           date=\currentdate,
-%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
-%C
-%C This module is part of the \CONTEXT\ macro||package and is
-%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
-%C details.
-
-%D This is ancient code .. but I see no need to rewrite it.
-
-if unknown context_tool :    input mp-tool ; fi ;
-if unknown context_shap :    input mp-shap ; fi ;
-if   known context_flow : endinput         ; fi ;
-
-boolean context_flow ; context_flow := true ;
-
-%D settings
-
-numeric flow_grid_width             ; flow_grid_width             := 60pt ;
-numeric flow_shape_width            ; flow_shape_width            := 45pt ;
-numeric flow_grid_height            ; flow_grid_height            := 40pt ;
-numeric flow_shape_height           ; flow_shape_height           := 30pt ;
-numeric flow_chart_offset           ; flow_chart_offset           :=  2pt ;
-color   flow_chart_background_color ; flow_chart_background_color := white ;
-boolean flow_show_mid_points        ; flow_show_mid_points        := false ;
-boolean flow_show_con_points        ; flow_show_con_points        := false ;
-boolean flow_show_all_points        ; flow_show_all_points        := false ;
-numeric flow_shape_line_width       ; flow_shape_line_width       := 2pt ;
-color   flow_shape_line_color       ; flow_shape_line_color       := .5white ;
-color   flow_shape_fill_color       ; flow_shape_fill_color       := .9white ;
-color   flow_connection_line_color  ; flow_connection_line_color  := .2white ;
-
-numeric flow_connection_line_width  ; flow_connection_line_width  := flow_shape_line_width ;
-
-numeric flow_connection_smooth_size ; flow_connection_smooth_size := 5pt ;
-numeric flow_connection_arrow_size  ; flow_connection_arrow_size  := 4pt ;
-numeric flow_connection_dash_size   ; flow_connection_dash_size   := 3pt ;
-
-numeric flow_max_x                  ; flow_max_x                  := 6 ;
-numeric flow_max_y                  ; flow_max_y                  := 4 ;
-
-boolean flow_smooth                 ; flow_smooth                 := true ;
-boolean flow_peepshape              ; flow_peepshape              := false ;
-boolean flow_arrowtip               ; flow_arrowtip               := true ;
-boolean flow_dashline               ; flow_dashline               := false ;
-boolean flow_forcevalid             ; flow_forcevalid             := false ;
-boolean flow_touchshape             ; flow_touchshape             := false ;
-boolean flow_showcrossing           ; flow_showcrossing           := false ;
-boolean flow_reverse_y              ; flow_reverse_y              := true ;
-
-picture flow_dash_pattern           ; flow_dash_pattern           := nullpicture ;
-
-numeric flow_shape_node             ; flow_shape_node             :=  0 ;
-numeric flow_shape_action           ; flow_shape_action           := 24 ;
-numeric flow_shape_procedure        ; flow_shape_procedure        :=  5 ;
-numeric flow_shape_product          ; flow_shape_product          := 12 ;
-numeric flow_shape_decision         ; flow_shape_decision         := 14 ;
-numeric flow_shape_archive          ; flow_shape_archive          := 19 ;
-numeric flow_shape_loop             ; flow_shape_loop             := 35 ;
-numeric flow_shape_wait             ; flow_shape_wait             :=  6 ;
-numeric flow_shape_subprocedure     ; flow_shape_subprocedure     := 20 ;
-numeric flow_shape_singledocument   ; flow_shape_singledocument   := 32 ;
-numeric flow_shape_multidocument    ; flow_shape_multidocument    := 33 ;
-numeric flow_shape_right            ; flow_shape_right            := 66 ;
-numeric flow_shape_left             ; flow_shape_left             := 67 ;
-numeric flow_shape_up               ; flow_shape_up               := 68 ;
-numeric flow_shape_down             ; flow_shape_down             := 69 ;
-
-% vardef some_shape_path (expr type) == imported from mp-shap
-
-def flow_show_shapes(expr n) =
-    flow_begin_chart(n,8,10) ;
-    flow_show_con_points := true ;
-    for i=0 upto 7 :
-        for j=0 upto 9 :
-            flow_new_shape(i+1,j+1,i*10+j);
-        endfor ;
-    endfor ;
-    flow_end_chart ;
-enddef ;
-
-%D connections
-
-def flow_new_chart =
-
-    flow_grid_width             := 60pt ;
-    flow_shape_width            := 45pt ;
-    flow_grid_height            := 40pt ;
-    flow_shape_height           := 30pt ;
-    flow_chart_offset           :=  2pt ;
-    flow_chart_background_color := white ;
-    flow_show_mid_points        := false ;
-    flow_show_con_points        := false ;
-    flow_show_all_points        := false ;
-    flow_shape_line_width       := 2pt ;
-    flow_shape_line_color       := .5white ;
-    flow_shape_fill_color       := .9white ;
-    flow_connection_line_color  := .2white ;
-    flow_connection_line_width  := flow_shape_line_width ;
-    flow_connection_smooth_size := 5pt ;
-    flow_connection_arrow_size  := 4pt ;
-    flow_connection_dash_size   := 3pt ;
-
-    flow_max_x                  := 6 ;
-    flow_max_y                  := 4 ;
-
-    flow_smooth                 := true  ;
-    flow_peepshape              := false ;
-    flow_arrowtip               := true  ;
-    flow_dashline               := false ;
-    flow_forcevalid             := false ;
-    flow_touchshape             := false ;
-    flow_showcrossing           := false ;
-    flow_reverse_y              := true ;
-
-    flow_dash_pattern           := nullpicture ;
-
-    numeric flow_xypoint       ; flow_xypoint := 0 ;
-    numeric flow_cpath         ; flow_cpath   := 0 ;
-
-    pair    flow_xypoints []   ;
-    boolean flow_xyfree   [][] ;
-    path    flow_xypath   [][] ;
-    numeric flow_xysx     [][] ;
-    numeric flow_xysy     [][] ;
-    color   flow_xyfill   [][] ;
-    color   flow_xydraw   [][] ;
-    numeric flow_xyline   [][] ;
-    boolean flow_xypeep   [][] ;
-    picture flow_xytext   [][] ;
-    picture flow_xylabel_l[][] ;
-    picture flow_xylabel_r[][] ;
-    picture flow_xylabel_t[][] ;
-    picture flow_xylabel_b[][] ;
-    picture flow_xyexit_l [][] ;
-    picture flow_xyexit_r [][] ;
-    picture flow_xyexit_t [][] ;
-    picture flow_xyexit_b [][] ;
-    path    flow_cpaths   []   ;
-    numeric flow_cline    []   ;
-    color   flow_ccolor   []   ;
-    boolean flow_carrow   []   ;
-    boolean flow_cdash    []   ;
-    boolean flow_ccross   []   ;
-
-    picture flow_tpicture[][]  ;
-    picture flow_bpicture[][]  ;
-    picture flow_lpicture[][]  ;
-    picture flow_rpicture[][]  ;
-
-    predefined_shapes[61] := (fullcircle scaled (1.5*predefined_shapes_yradius) xscaled (flow_grid_height/flow_grid_width)) ;
-    predefined_shapes[62] := (fullcircle scaled (2.0*predefined_shapes_yradius) xscaled (flow_grid_height/flow_grid_width)) ;
-
-enddef ;
-
-flow_new_chart ;
-
-def flow_y_pos(expr y) =
-    if flow_reverse_y :
-        flow_max_y + 1 - y
-    else :
-        y
-    fi
-enddef ;
-
-def flow_initialize_grid(expr maxx, maxy) =
-    flow_max_x := maxx ;
-    flow_max_y := maxy ;
-    flow_dsp_x := 0 ;
-    flow_dsp_y := 0 ;
-    for x=1 upto flow_max_x :
-        for y=1 upto flow_max_y :
-            flow_xyfree[x][y] := true ;
-            flow_xyfill[x][y] := flow_shape_fill_color ;
-            flow_xydraw[x][y] := flow_shape_line_color ;
-            flow_xyline[x][y] := flow_shape_line_width ;
-        endfor ;
-    endfor ;
-enddef ;
-
-def flow_scaled_to_grid =
-    xscaled flow_grid_width yscaled flow_grid_height
-enddef ;
-
-def flow_xy_offset(expr x, y) =
-    (x+.5,y+.5)
-enddef ;
-
-def flow_draw_shape(expr x, yy, p, sx, sy) =
-    begingroup ;
-        save y ; numeric y ;
-        y := flow_y_pos(yy) ;
-        flow_xypath [x][y] := (p xscaled sx yscaled sy) shifted flow_xy_offset(x,y) ;
-        flow_xyfree [x][y] := false ;
-        flow_xysx   [x][y] := sx ;
-        flow_xysy   [x][y] := sy ;
-        flow_xyfill [x][y] := flow_shape_fill_color ;
-        flow_xydraw [x][y] := flow_shape_line_color ;
-        flow_xyline [x][y] := flow_shape_line_width ;
-        flow_xypeep [x][y] := flow_peepshape ;
-    endgroup ;
-enddef ;
-
-vardef flow_i_point (expr x, y, p, t) =
-    begingroup ;
-        save q, ok ; pair q ; boolean ok ;
-        q := flow_xypath[x][y] intersection_point ((p) shifted flow_xy_offset(x,y)) ;
-        ok := true ;
-        if not ok :
-            message (t & " of shape (" & decimal x & "," & decimal y & ") limited") ;
-        fi ;
-        q
-    endgroup
-enddef ;
-
-vardef flow_trimmed (expr x, y, z, t) =
-    if flow_touchshape and t :
-        flow_xyline[x][y]/z
-    else :
-        epsilon
-    fi
-enddef ;
-
-numeric flow_zfactor ; flow_zfactor := 1/3 ;
-
-vardef flow_xy_bottom (expr x, y, z, t) =
-    flow_i_point(x, y, ((0,0)--(0,-2)) shifted (flow_zfactor*z*flow_xysx[x][y],0), "bottom")
-    shifted(0,-flow_trimmed(x,y,flow_grid_height,t))
-enddef ;
-
-vardef flow_xy_top (expr x, y, z, t) =
-    flow_i_point (x, y, ((0,0)--(0,2))  shifted (flow_zfactor*z*flow_xysx[x][y],0), "top")
-    shifted(0,flow_trimmed(x,y,flow_grid_height,t))
-enddef ;
-
-vardef flow_xy_left (expr x, y, z, t) =
-    flow_i_point (x, y, ((0,0)--(-2,0)) shifted (0,flow_zfactor*z*flow_xysy[x][y]), "left")
-    shifted(-flow_trimmed(x,y,flow_grid_width,t),0)
-enddef ;
-
-vardef flow_xy_right (expr x, y, z, t) =
-    flow_i_point (x, y, ((0,0)--(2,0))  shifted (0,flow_zfactor*z*flow_xysy[x][y]), "right")
-    shifted(flow_trimmed(x,y,flow_grid_width,t),0)
-enddef ;
-
-def flow_flush_shapes =
-    for x=1 upto flow_max_x :
-        for y=1 upto flow_max_y :
-            flow_flush_shape(x, y) ;
-        endfor ;
-    endfor ;
-enddef ;
-
-def flow_flush_pictures =
-    for x=1 upto flow_max_x :
-        for y=1 upto flow_max_y :
-            flow_flush_picture(x, y) ;
-        endfor ;
-    endfor ;
-enddef ;
-
-def flow_draw_connection_point(expr x, y, z) =
-    pickup pencircle scaled if (z=0): 2 fi flow_xyline[x][y] ;
-    drawdot flow_xy_bottom(x,y,z,false) flow_scaled_to_grid withcolor (1,0,0) ;
-    drawdot flow_xy_top   (x,y,z,false) flow_scaled_to_grid withcolor (0,1,0) ;
-    drawdot flow_xy_left  (x,y,z,false) flow_scaled_to_grid withcolor (0,0,1) ;
-    drawdot flow_xy_right (x,y,z,false) flow_scaled_to_grid withcolor (1,1,0) ;
-enddef ;
-
-def flow_flush_shape(expr x, yy) =
-    begingroup ;
-        save y ; numeric y ;
-        y := flow_y_pos(yy) ;
-        if not flow_xyfree[x][y] :
-            pickup pencircle scaled flow_xyline[x][y] ;
-            if flow_xypeep[x][y] :
-                fill (flow_xypath[x][y] peepholed (unitsquare shifted (x,y)))
-                    flow_scaled_to_grid withpen pencircle scaled 0
-                    withcolor flow_chart_background_color ;
-            else :
-                fill flow_xypath[x][y] flow_scaled_to_grid withcolor flow_xyfill[x][y] ;
-            fi ;
-            draw flow_xypath[x][y] flow_scaled_to_grid withcolor flow_xydraw[x][y] ;
-            if flow_show_con_points or flow_show_all_points :
-                flow_draw_connection_point(x, y, 0) ;
-            fi ;
-            if flow_show_all_points :
-                for i=-1 upto 1 :
-                    flow_draw_connection_point(x, y, i) ;
-                endfor ;
-            fi ;
-        fi ;
-    endgroup ;
-enddef ;
-
-vardef flow_points_initialized(expr xfrom, yfrom, xto, yto, n) =
-    if not flow_xyfree[xfrom][yfrom] and not flow_xyfree[xto][yto] :
-        flow_xypoint := n ; true
-    else :
-        flow_xypoint := 0 ; false
-    fi
-enddef ;
-
-def flow_collapse_points = % this is now an mp-tool macro
-    begingroup ;
-        % remove redundant points
-        save n ; numeric n ;
-        n := 1 ;
-        for i=2 upto flow_xypoint :
-            if not (flow_xypoints[i] = flow_xypoints[n]) :
-                n := n + 1 ;
-                flow_xypoints[n] := flow_xypoints[i]
-            fi ;
-        endfor ;
-        flow_xypoint := n ;
-        % make straight lines
-        if flow_xypoints[2] = flow_xypoints[flow_xypoint-1] :
-            flow_xypoints[3] := flow_xypoints[flow_xypoint] ;
-            flow_xypoint := 3 ;
-        fi ;
-    endgroup ;
-enddef ;
-
-vardef flow_smooth_connection(expr a,b) =
-    if ypart a = ypart b :
-        a shifted (  if xpart a >= xpart b : - fi (flow_connection_smooth_size/flow_grid_width ),0)
-    else :
-        a shifted (0,if ypart a >= ypart b : - fi (flow_connection_smooth_size/flow_grid_height)  )
-    fi
-enddef ;
-
-vardef flow_trim_points =
-    begingroup
-        save p, a, b, d, i ; numeric a, b ; path p ; pair d ;
-        p := for i=1 upto flow_xypoint-1 : flow_xypoints[i]-- endfor flow_xypoints[flow_xypoint] ;
-        if flow_touchshape :
-            a := flow_shape_line_width/flow_grid_width ;
-            b := flow_shape_line_width/flow_grid_height ;
-        else :
-            a := epsilon ;
-            b := epsilon ;
-        fi ;
-        d := direction infinity of p ;
-        flow_xypoints[flow_xypoint] := flow_xypoints[flow_xypoint] shifted
-        if     xpart d < 0 : (+a,0) ;
-        elseif xpart d > 0 : (-a,0) ;
-        elseif ypart d < 0 : (0,+b) ;
-        elseif ypart d > 0 : (0,-b) ;
-        else               : origin ;
-        fi ;
-        d := direction 0 of p ;
-        flow_xypoints[1] := flow_xypoints[1] shifted
-        if     xpart d < 0 : (-a,0) ;
-        elseif xpart d > 0 : (+a,0) ;
-        elseif ypart d < 0 : (0,-b) ;
-        elseif ypart d > 0 : (0,+b) ;
-        else               : origin ;
-        fi ;
-    endgroup
-enddef ;
-
-vardef flow_trim_points = enddef ;
-
-vardef flow_connection_path =
-    if flow_reverse_connection : reverse fi (flow_xypoints[1] --
-    for i=2 upto flow_xypoint-1 :
-        if flow_smooth :
-            flow_smooth_connection(flow_xypoints[i],flow_xypoints[i-1]) ..
-            controls flow_xypoints[i] and flow_xypoints[i] ..
-            flow_smooth_connection(flow_xypoints[i],flow_xypoints[i+1]) --
-        else :
-            flow_xypoints[i] --
-        fi
-    endfor
-    flow_xypoints[flow_xypoint])
-enddef ;
-
-def flow_draw_connection =
-    if flow_xypoint > 0 :
-        flow_collapse_points ;
-        flow_trim_points ;
-        flow_cpath := flow_cpath + 1 ;
-        flow_cpaths[flow_cpath] := flow_connection_path flow_scaled_to_grid ;
-        flow_cline[flow_cpath]  := flow_connection_line_width ;
-        flow_ccolor[flow_cpath] := flow_connection_line_color ;
-        flow_carrow[flow_cpath] := flow_arrowtip ;
-        flow_cdash[flow_cpath]  := flow_dashline ;
-        flow_ccross[flow_cpath] := flow_showcrossing ;
-    else :
-        message("no connection defined") ;
-    fi ;
-    flow_reverse_connection := false ;
-enddef ;
-
-def flow_flush_connections = % protect locals
-    begingroup ;
-    save ip, crossing, cp ; numeric ip ; boolean crossing ; path cp ;
-    ahlength := flow_connection_arrow_size ;
-    flow_dash_pattern := dashpattern(on flow_connection_dash_size off flow_connection_dash_size) ;
-    for i=1 upto flow_cpath :
-        if flow_ccross[i] :
-            crossing := false ;
-            for j=1 upto i :
-                if not  (point infinity of flow_cpaths[i] = point infinity of flow_cpaths[j]) :
-                    ip := flow_cpaths[i] intersection_point flow_cpaths[j] ;
-                    if intersection_found : crossing := true fi ;
-                fi ;
-            endfor ;
-            if crossing :
-                pickup pencircle scaled 2flow_cline[i] ;
-                cp := flow_cpaths[i] ;
-                cp := cp cutbefore point .05 length cp of cp ;
-                cp := cp cutafter  point .95 length cp of cp ;
-                draw cp withcolor flow_chart_background_color ;
-            fi ;
-        fi ;
-        pickup pencircle scaled flow_cline[i] ;
-        if flow_carrow[i] :
-            if flow_cdash[i] :
-                drawarrow flow_cpaths[i] withcolor flow_ccolor[i] dashed flow_dash_pattern ;
-            else :
-                drawarrow flow_cpaths[i] withcolor flow_ccolor[i] ;
-            fi ;
-        else :
-            if flow_cdash[i] :
-                draw flow_cpaths[i] withcolor flow_ccolor[i] dashed flow_dash_pattern ;
-            else :
-                draw flow_cpaths[i] withcolor flow_ccolor[i] ;
-            fi ;
-        fi ;
-        flow_draw_midpoint(i) ;
-    endfor ;
-    endgroup ;
-enddef ;
-
-def flow_draw_midpoint (expr n) =
-    begingroup
-        save p ; pair p ;
-        p := point .5*length(flow_cpaths[n]) of flow_cpaths[n];
-        pickup pencircle scaled 2flow_cline[n] ;
-        if flow_show_mid_points :
-            drawdot p withcolor .7white ;
-        fi ;
-    endgroup ;
-enddef ;
-
-def flow_flush_picture(expr x, yy) =
-    begingroup ; save y ; numeric y ;
-    y := flow_y_pos(yy) ;
-    if known flow_xytext[x][y] :
-        begingroup ;
-            % flow_xypath[x][y]
-            save p, offset ; path p ; pair offset ;
-            offset := flow_xy_offset((x+0.5)*flow_grid_width,(flow_max_y-y+1.5)*flow_grid_height) ;
-            offset := offset shifted (-flow_xyline[x][y]/4,-flow_xyline[x][y]/4) ; % terrible hack (some compensation)
-            p := fullsquare
-                xscaled flow_grid_width
-                yscaled flow_grid_height
-                shifted offset ;
-            if known flow_xytext[x][y]:
-                draw flow_xytext[x][y] shifted offset ;
-            fi ;
-            if known flow_xylabel_t[x][y] :
-                label.urt(flow_xylabel_t[x][y],0.5[ulcorner p,urcorner p]) ;
-            fi ;
-            if known flow_xylabel_b[x][y] :
-                label.lrt(flow_xylabel_b[x][y],0.5[llcorner p,lrcorner p]) ;
-            fi ;
-            if known flow_xylabel_l[x][y] :
-                label.ulft(flow_xylabel_l[x][y],0.5[ulcorner p,llcorner p]) ;
-            fi ;
-            if known flow_xylabel_r[x][y] :
-                label.urt (flow_xylabel_r[x][y],0.5[urcorner p,lrcorner p]) ;
-            fi ;
-            if known flow_xyexit_t[x][y] :
-                label.top(flow_xyexit_t[x][y],0.5[ulcorner p,urcorner p] shifted (0, flow_grid_height/2)) ;
-            fi ;
-            if known flow_xyexit_b[x][y] :
-                label.bot(flow_xyexit_b[x][y],0.5[llcorner p,lrcorner p] shifted (0,-flow_grid_height/2)) ;
-            fi ;
-            if known flow_xyexit_l[x][y] :
-                label.lft(flow_xyexit_l[x][y],0.5[ulcorner p,llcorner p] shifted (-flow_grid_width/2,0)) ;
-            fi ;
-            if known flow_xyexit_r[x][y] :
-                label.rt (flow_xyexit_r[x][y],0.5[urcorner p,lrcorner p] shifted ( flow_grid_width/2,0)) ;
-            fi ;
-        endgroup ;
-    fi ;
-    endgroup ;
-enddef ;
-
-def flow_chart_draw_text(expr x, y, p) =
-    flow_xytext[x][y] := p ;
-enddef ;
-
-def flow_chart_draw_label_t(expr x, y, p) = flow_xylabel_t[x][y] := p ; enddef ;
-def flow_chart_draw_label_b(expr x, y, p) = flow_xylabel_b[x][y] := p ; enddef ;
-def flow_chart_draw_label_l(expr x, y, p) = flow_xylabel_l[x][y] := p ; enddef ;
-def flow_chart_draw_label_r(expr x, y, p) = flow_xylabel_r[x][y] := p ; enddef ;
-
-def flow_chart_draw_exit_t (expr x, y, p) = flow_xyexit_t [x][y] := p ; enddef ;
-def flow_chart_draw_exit_b (expr x, y, p) = flow_xyexit_b [x][y] := p ; enddef ;
-def flow_chart_draw_exit_l (expr x, y, p) = flow_xyexit_l [x][y] := p ; enddef ;
-def flow_chart_draw_exit_r (expr x, y, p) = flow_xyexit_r [x][y] := p ; enddef ;
-
-boolean flow_reverse_connection ; flow_reverse_connection := false ;
-
-vardef flow_up_on_grid (expr n) =
-    (xpart flow_xypoints[n],(ypart flow_xypoints[n]+1) div 1)
-enddef ;
-
-vardef flow_down_on_grid (expr n) =
-    (xpart flow_xypoints[n],(ypart flow_xypoints[n]) div 1)
-enddef ;
-
-vardef flow_left_on_grid (expr n) =
-    ((xpart flow_xypoints[n]) div 1, ypart flow_xypoints[n])
-enddef ;
-
-vardef flow_right_on_grid (expr n) =
-    ((xpart flow_xypoints[n]+1) div 1, ypart flow_xypoints[n])
-enddef ;
-
-vardef flow_x_on_grid (expr n, xfrom, xto, zfrom) =
-    if (xfrom = xto) and not (zfrom = 0) :
-        if (zfrom=1) : flow_right_on_grid(2) else : flow_left_on_grid(2) fi
-    elseif xpart flow_xypoints[1] < xpart flow_xypoints[6] :
-        flow_right_on_grid(n)
-    else :
-        flow_left_on_grid(n)
-    fi
-enddef ;
-
-vardef flow_y_on_grid (expr n, yfrom, yto, zfrom) =
-    if (yfrom = yto) and not (zfrom = 0) :
-        if (zfrom = 1) : flow_up_on_grid(2) else : flow_down_on_grid(2) fi
-    elseif ypart flow_xypoints[1] < ypart flow_xypoints[6] :
-        flow_up_on_grid(n)
-    else :
-        flow_down_on_grid(n)
-    fi
-enddef ;
-
-vardef flow_xy_on_grid (expr n, m) =
-    (xpart flow_xypoints[n], ypart flow_xypoints[m])
-enddef ;
-
-vardef flow_down_to_grid (expr a,b) =
-    (xpart flow_xypoints[a], ypart flow_xypoints[if ypart flow_xypoints[a]<ypart flow_xypoints[b] : a else : b fi])
-enddef ;
-
-vardef flow_up_to_grid (expr a,b) =
-    (xpart flow_xypoints[a], ypart flow_xypoints[if ypart flow_xypoints[a]>ypart flow_xypoints[b] : a else : b fi])
-enddef ;
-
-vardef flow_left_to_grid (expr a,b) =
-    (xpart flow_xypoints[if xpart flow_xypoints[a]<xpart flow_xypoints[b] : a else : b fi], ypart flow_xypoints[a])
-enddef ;
-
-vardef flow_right_to_grid (expr a,b) =
-    (xpart flow_xypoints[if xpart flow_xypoints[a]>xpart flow_xypoints[b] : a else : b fi], ypart flow_xypoints[a])
-enddef ;
-
-vardef flow_valid_connection (expr xfrom, yfrom, xto, yto) =
-    begingroup ;
-        save ok, vc, pp ; boolean ok ; pair vc ; path pp ;
-        save flow_xyfirst, flow_xylast ; pair flow_xyfirst, flow_xylast ;
-        % check for slanted lines
-        ok := true ;
-        for i=1 upto flow_xypoint-1 :
-            if not ((xpart flow_xypoints[i]=xpart flow_xypoints[i+1]) or (ypart flow_xypoints[i]=ypart flow_xypoints[i+1])) :
-                ok := false ;
-            fi ;
-        endfor ;
-        if not ok :
-            % message("slanted");
-            false
-        elseif flow_forcevalid :
-            % message("force");
-            true
-        elseif (xfrom=xto) and (yfrom=yto) :
-            % message("self");
-            false
-        else :
-            % check for crossing shapes
-            flow_xyfirst := flow_xypoints[1] ;
-            flow_xylast := flow_xypoints[flow_xypoint] ;
-            flow_trim_points ;
-            pp := for i=1 upto flow_xypoint-1 : flow_xypoints[i]-- endfor flow_xypoints[flow_xypoint] ;
-            flow_xypoints[1] := flow_xyfirst ;
-            flow_xypoints[flow_xypoint] := flow_xylast ;
-            for i=1 upto flow_max_x :
-                for j=1 upto flow_max_y :                % was bug: xfrom,yto
-                    if not ( ( (i,j)=(xfrom,yfrom) ) or ( (i,j)=(xto,yto) ) ) :
-                        if not flow_xyfree[i][j] :
-                            vc := pp intersection_point flow_xypath[i][j] ;
-                            if intersection_found :
-                                ok := false
-                            fi ;
-                        fi ;
-                    fi ;
-                endfor ;
-            endfor ;
-            % if not ok: message("crossing") ; fi ;
-            ok
-        fi
-    endgroup
-enddef ;
-
-def flow_connect_top_bottom (expr xfrom, yyfrom, zfrom) (expr xto, yyto, zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,6) :
-        flow_xypoints[1] := flow_xy_top(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[6] := flow_xy_bottom(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_up_on_grid(1) ;
-        flow_xypoints[5] := flow_down_on_grid(6) ;
-        flow_xypoints[3] := flow_up_to_grid(2,5) ;
-        flow_xypoints[4] := flow_up_to_grid(2,5) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_x_on_grid(2,xfrom,xto,zfrom) ;
-            flow_xypoints[4] := flow_xy_on_grid(3,5) ;
-        fi ;
-        %%%% begin experiment
-        flow_xypoints[3] := flow_xypoints[3] shifted (flow_dsp_x,0) ;
-        flow_xypoints[4] := flow_xypoints[4] shifted (flow_dsp_x,0) ;
-        if flow_dsp_y>0 :
-            flow_xypoints[2] := flow_xypoints[2] shifted (0,flow_dsp_y) ;
-            flow_xypoints[3] := flow_xypoints[3] shifted (0,flow_dsp_y) ;
-        elseif flow_dsp_y<0 :
-            flow_xypoints[4] := flow_xypoints[4] shifted (0,flow_dsp_y) ;
-            flow_xypoints[5] := flow_xypoints[5] shifted (0,flow_dsp_y) ;
-        fi
-        %%%% end experiment
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_left_right (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,6) :
-        flow_xypoints[1] := flow_xy_left(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[6] := flow_xy_right(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_left_on_grid(1) ;
-        flow_xypoints[5] := flow_right_on_grid(6) ;
-        flow_xypoints[3] := flow_left_to_grid(2,5) ;
-        flow_xypoints[4] := flow_left_to_grid(2,5) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_y_on_grid(2,yfrom,yto,zfrom) ;
-            flow_xypoints[4] := flow_xy_on_grid(5,3) ;
-        fi ;
-        flow_draw_connection ;
-  fi ;
-enddef ;
-
-def flow_connect_left_top (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,5) :
-        flow_xypoints[1] := flow_xy_left(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[5] := flow_xy_top(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_left_on_grid(1) ;
-        flow_xypoints[4] := flow_up_on_grid(5) ;
-        flow_xypoints[3] := flow_left_to_grid(2,5) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_xy_on_grid(2,4) ;
-        fi ;
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_left_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,5) :
-        flow_xypoints[1] := flow_xy_left(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[5] := flow_xy_bottom(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_left_on_grid(1) ;
-        flow_xypoints[4] := flow_down_on_grid(5) ;
-        flow_xypoints[3] := flow_left_to_grid(2,5) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_xy_on_grid(2,4) ;
-        fi ;
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_right_top (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,5) :
-        flow_xypoints[1] := flow_xy_right(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[5] := flow_xy_top(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_right_on_grid(1) ;
-        flow_xypoints[4] := flow_up_on_grid(5) ;
-        flow_xypoints[3] := flow_right_to_grid(2,5) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_xy_on_grid(2,4) ;
-        fi ;
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_right_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,5) :
-        flow_xypoints[1] := flow_xy_right(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[5] := flow_xy_bottom(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_right_on_grid(1) ;
-        flow_xypoints[4] := flow_down_on_grid(5) ;
-        flow_xypoints[3] := flow_right_to_grid(2,5) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_xy_on_grid(2,4) ;
-        fi ;
-        %%%% begin experiment
-        flow_xypoints[2] := flow_xypoints[2] shifted (flow_dsp_x,0) ;
-        flow_xypoints[3] := flow_xypoints[3] shifted (flow_dsp_x,0) ;
-        if flow_dsp_y>0 :
-          flow_xypoints[3] := flow_xypoints[3] shifted (0,-flow_dsp_y) ;
-          flow_xypoints[4] := flow_xypoints[4] shifted (0,-flow_dsp_y) ;
-        elseif flow_dsp_y<0 :
-          flow_xypoints[3] := flow_xypoints[3] shifted (0,flow_dsp_y) ;
-          flow_xypoints[4] := flow_xypoints[4] shifted (0,flow_dsp_y) ;
-        fi
-        %%%% end experiment
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_left_left (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,6) :
-        flow_xypoints[1] := flow_xy_left(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[6] := flow_xy_left(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_left_on_grid(1) ;
-        flow_xypoints[5] := flow_left_on_grid(6) ;
-        flow_xypoints[3] := flow_left_to_grid(2,5) ;
-        flow_xypoints[4] := flow_left_to_grid(5,2) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_y_on_grid(2,yfrom,yto,zfrom) ;
-            flow_xypoints[4] := flow_xy_on_grid(5,3) ;
-        fi ;
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_right_right (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,6) :
-        flow_xypoints[1] := flow_xy_right(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[6] := flow_xy_right(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_right_on_grid(1) ;
-        flow_xypoints[5] := flow_right_on_grid(6) ;
-        flow_xypoints[3] := flow_right_to_grid(2,5) ;
-        flow_xypoints[4] := flow_right_to_grid(5,2) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-          flow_xypoints[3] := flow_y_on_grid(2,yfrom,yto,zfrom) ;
-          flow_xypoints[4] := flow_xy_on_grid(5,3) ;
-        fi ;
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_top_top (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,6) :
-        flow_xypoints[1] := flow_xy_top(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[6] := flow_xy_top(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_up_on_grid(1) ;
-        flow_xypoints[5] := flow_up_on_grid(6) ;
-        flow_xypoints[3] := flow_up_to_grid(2,5) ;
-        flow_xypoints[4] := flow_up_to_grid(5,2) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_x_on_grid(2,xfrom,xto,zfrom) ;
-            flow_xypoints[4] := flow_xy_on_grid(3,5) ;
-        fi ;
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_bottom_bottom (expr xfrom,yyfrom,zfrom) (expr xto,yyto,zto) =
-    yfrom := flow_y_pos(yyfrom) ;
-    yto := flow_y_pos(yyto) ;
-    if flow_points_initialized(xfrom,yfrom,xto,yto,6) :
-        flow_xypoints[1] := flow_xy_bottom(xfrom,yfrom,zfrom,true) ;
-        flow_xypoints[6] := flow_xy_bottom(xto,yto,zto,true) ;
-        flow_xypoints[2] := flow_down_on_grid(1) ;
-        flow_xypoints[5] := flow_down_on_grid(6) ;
-        flow_xypoints[3] := flow_down_to_grid(2,5) ;
-        flow_xypoints[4] := flow_down_to_grid(5,2) ;
-        if not flow_valid_connection(xfrom,yfrom,xto,yto) :
-            flow_xypoints[3] := flow_x_on_grid(2,xfrom,xto,zfrom) ;
-            flow_xypoints[4] := flow_xy_on_grid(3,5) ;
-        fi ;
-        %%%% begin experiment
-        flow_xypoints[3] := flow_xypoints[3] shifted (flow_dsp_x,0) ;
-        flow_xypoints[4] := flow_xypoints[4] shifted (flow_dsp_x,0) ;
-        if flow_dsp_y<0 :
-            flow_xypoints[2] := flow_xypoints[2] shifted (0,-flow_dsp_y) ;
-            flow_xypoints[3] := flow_xypoints[3] shifted (0,-flow_dsp_y) ;
-        elseif flow_dsp_y>0 :
-            flow_xypoints[4] := flow_xypoints[4] shifted (0,flow_dsp_y) ;
-            flow_xypoints[5] := flow_xypoints[5] shifted (0,flow_dsp_y) ;
-        fi
-        %%%% end experiment
-        flow_draw_connection ;
-    fi ;
-enddef ;
-
-def flow_connect_bottom_top (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-    flow_reverse_connection := true ;
-    flow_connect_top_bottom (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def flow_connect_right_left (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-    flow_reverse_connection := true ;
-    flow_connect_left_right (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def flow_connect_top_left (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-    flow_reverse_connection := true ;
-    flow_connect_left_top(xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def flow_connect_bottom_left (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-    flow_reverse_connection := true ;
-    flow_connect_left_bottom (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def flow_connect_top_right (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-    flow_reverse_connection := true ;
-    flow_connect_right_top (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def flow_connect_bottom_right (expr xfrom,yfrom,zfrom) (expr xto,yto,zto) =
-    flow_reverse_connection := true ;
-    flow_connect_right_bottom (xto,yto,zto) (xfrom,yfrom,zfrom) ;
-enddef ;
-
-def flow_draw_test_shape(expr x, y) =
-    flow_draw_shape(x,y,fullcircle, .7, .7) ;
-enddef ;
-
-def flow_draw_test_shapes =
-    for i=1 upto flow_max_x :
-        for j=1 upto flow_max_y :
-            flow_draw_test_shape(i,j) ;
-        endfor ;
-    endfor ;
-enddef;
-
-def flow_draw_test_area =
-    pickup pencircle scaled .5flow_shape_line_width ;
-    draw (unitsquare xscaled flow_max_x yscaled flow_max_y shifted (1,1)) flow_scaled_to_grid withcolor blue ;
-enddef ;
-
-def flow_show_connection(expr n, m) =
-
-    flow_begin_chart(100+n,6,6) ;
-
-        flow_draw_test_area ;
-
-        flow_smooth   := true ;
-        flow_arrowtip := true ;
-        flow_dashline := true ;
-
-        flow_draw_test_shape(2,2) ; flow_draw_test_shape(4,5) ;
-        flow_draw_test_shape(3,3) ; flow_draw_test_shape(5,1) ;
-        flow_draw_test_shape(2,5) ; flow_draw_test_shape(1,3) ;
-        flow_draw_test_shape(6,2) ; flow_draw_test_shape(4,6) ;
-
-        if     (m=1) :
-            flow_connect_top_bottom (2,2,0) (4,5,0) ;
-            flow_connect_top_bottom (3,3,0) (5,1,0) ;
-            flow_connect_top_bottom (2,5,0) (1,3,0) ;
-            flow_connect_top_bottom (6,2,0) (4,6,0) ;
-        elseif (m=2) :
-            flow_connect_top_top (2,2,0) (4,5,0) ;
-            flow_connect_top_top (3,3,0) (5,1,0) ;
-            flow_connect_top_top (2,5,0) (1,3,0) ;
-            flow_connect_top_top (6,2,0) (4,6,0) ;
-        elseif (m=3) :
-            flow_connect_bottom_bottom (2,2,0) (4,5,0) ;
-            flow_connect_bottom_bottom (3,3,0) (5,1,0) ;
-            flow_connect_bottom_bottom (2,5,0) (1,3,0) ;
-            flow_connect_bottom_bottom (6,2,0) (4,6,0) ;
-        elseif (m=4) :
-            flow_connect_left_right (2,2,0) (4,5,0) ;
-            flow_connect_left_right (3,3,0) (5,1,0) ;
-            flow_connect_left_right (2,5,0) (1,3,0) ;
-            flow_connect_left_right (6,2,0) (4,6,0) ;
-        elseif (m=5) :
-            flow_connect_left_left (2,2,0) (4,5,0) ;
-            flow_connect_left_left (3,3,0) (5,1,0) ;
-            flow_connect_left_left (2,5,0) (1,3,0) ;
-            flow_connect_left_left (6,2,0) (4,6,0) ;
-        elseif (m=6) :
-            flow_connect_right_right (2,2,0) (4,5,0) ;
-            flow_connect_right_right (3,3,0) (5,1,0) ;
-            flow_connect_right_right (2,5,0) (1,3,0) ;
-            flow_connect_right_right (6,2,0) (4,6,0) ;
-        elseif (m=7) :
-            flow_connect_left_top (2,2,0) (4,5,0) ;
-            flow_connect_left_top (3,3,0) (5,1,0) ;
-            flow_connect_left_top (2,5,0) (1,3,0) ;
-            flow_connect_left_top (6,2,0) (4,6,0) ;
-        elseif (m=8) :
-            flow_connect_left_bottom (2,2,0) (4,5,0) ;
-            flow_connect_left_bottom (3,3,0) (5,1,0) ;
-            flow_connect_left_bottom (2,5,0) (1,3,0) ;
-            flow_connect_left_bottom (6,2,0) (4,6,0) ;
-        elseif (m=9) :
-            flow_connect_right_top (2,2,0) (4,5,0) ;
-            flow_connect_right_top (3,3,0) (5,1,0) ;
-            flow_connect_right_top (2,5,0) (1,3,0) ;
-            flow_connect_right_top (6,2,0) (4,6,0) ;
-        else :
-            flow_connect_right_bottom (2,2,0) (4,5,0) ;
-            flow_connect_right_bottom (3,3,0) (5,1,0) ;
-            flow_connect_right_bottom (2,5,0) (1,3,0) ;
-            flow_connect_right_bottom (6,2,0) (4,6,0) ;
-        fi ;
-
-    flow_end_chart ;
-
-enddef ;
-
-def flow_show_connections =
-    for f=1 upto 10 :
-        flow_show_connection(f,f) ;
-    endfor ;
-enddef ;
-
-%D charts
-
-def flow_clip_chart(expr minx, miny, maxx, maxy) =
-    flow_cmin_x := minx ;
-    flow_cmax_x := maxx ;
-    flow_cmin_y := miny ;
-    flow_cmax_y := maxy ;
-enddef ;
-
-def flow_begin_chart(expr n, maxx, maxy) =
-    flow_new_chart ;
-    flow_chart_figure := n ;
-    flow_chart_scale := 1 ;
-    if flow_chart_figure>0:
-        beginfig(flow_chart_figure) ;
-    fi ;
-    flow_initialize_grid (maxx, maxy) ;
-    bboxmargin := 0 ;
-    flow_cmin_x := 1 ;
-    flow_cmax_x := maxx ;
-    flow_cmin_y := 1 ;
-    flow_cmax_y := maxy ;
-enddef ;
-
-def flow_end_chart =
-    begingroup ;
-    save p ; path p ;
-    flow_flush_shapes ;
-    flow_flush_connections ;
-    flow_flush_pictures ;
-    flow_cmin_x := flow_cmin_x ;
-    flow_cmax_x := flow_cmin_x+flow_cmax_x ;
-    flow_cmin_y := flow_cmin_y-1 ;
-    flow_cmax_y := flow_cmin_y+flow_cmax_y ;
-    if flow_reverse_y :
-        flow_cmin_y := flow_y_pos(flow_cmin_y) ;
-        flow_cmax_y := flow_y_pos(flow_cmax_y) ;
-    fi ;
-    p := (((flow_cmin_x,flow_cmin_y)--(flow_cmax_x,flow_cmin_y)--
-         (flow_cmax_x,flow_cmax_y)--(flow_cmin_x,flow_cmax_y)--cycle))
-       flow_scaled_to_grid ;
-    %draw p withcolor red ;
-    p := p enlarged flow_chart_offset ;
-    clip currentpicture to p ;
-    setbounds currentpicture to p ;
-    endgroup ;
-    currentpicture := currentpicture scaled flow_chart_scale ;
-    if flow_chart_figure>0:
-        endfig ;
-    fi ;
-enddef ;
-
-def flow_new_shape(expr x, y, n) =
-    if known n :
-        if (x>0) and (x<=flow_max_x) and (y>0) and (y<=flow_max_y) :
-            flow_draw_shape(x,y,some_shape_path(n), flow_shape_width/flow_grid_width, flow_shape_height/flow_grid_height) ;
-        else :
-            message ("shape outside grid ignored") ;
-        fi ;
-    else :
-        message ("shape not known" ) ;
-    fi ;
-enddef ;
-
-def flow_begin_sub_chart =
-    begingroup ;
-    save    flow_shape_line_width, flow_connection_line_width ;
-    save    flow_shape_line_color, flow_shape_fill_color, flow_connection_line_color ;
-    color   flow_shape_line_color, flow_shape_fill_color, flow_connection_line_color ;
-    save    flow_smooth, flow_arrowtip, flow_dashline, flow_peepshape ;
-    boolean flow_smooth, flow_arrowtip, flow_dashline, flow_peepshape ;
-enddef ;
-
-def flow_end_sub_chart =
-    endgroup ;
-enddef ;
-
diff --git a/metapost/context/base/mp-step.mp b/metapost/context/base/mp-step.mpii
index d602f7014..d602f7014 100644
--- a/metapost/context/base/mp-step.mp
+++ b/metapost/context/base/mp-step.mpii
diff --git a/metapost/context/base/mp-step.mpiv b/metapost/context/base/mp-step.mpiv
new file mode 100644
index 000000000..dbbc38231
--- /dev/null
+++ b/metapost/context/base/mp-step.mpiv
@@ -0,0 +1,375 @@
+%D \module
+%D   [       file=mp-cell.mpiv, % mp-step.mp,
+%D        version=2010.10.07,   % 2001.05.22,
+%D          title=\CONTEXT\ \METAPOST\ graphics,
+%D       subtitle=steps,
+%D         author=Hans Hagen,
+%D           date=\currentdate,
+%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
+%C
+%C This module is part of the \CONTEXT\ macro||package and is
+%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
+%C details.
+
+if unknown context_tool :    input mp-tool ; fi ;
+if   known context_cell : endinput         ; fi ;
+
+boolean context_cell ; context_cell := true ;
+
+def initialize_step_variables =
+    save
+        text_fill_color, text_line_color, text_line_width, text_offset,
+        cell_fill_color, cell_line_color, cell_line_width, cell_offset,
+        line_line_color, line_line_width, line_alternative,
+        line_distance, cell_distance_y, cell_distance_x,
+        nofcells, chart_vertical ;
+
+    color   text_line_color     ; text_line_color     := red ;
+    color   cell_line_color     ; cell_line_color     := blue ;
+    color   line_line_color     ; line_line_color     := green ;
+
+    color   text_fill_color     ; text_fill_color     := white ;
+    color   cell_fill_color     ; cell_fill_color     := white ;
+
+    numeric text_line_width     ; text_line_width     := 2pt ;
+    numeric cell_line_width     ; cell_line_width     := 2pt ;
+    numeric line_line_width     ; line_line_width     := 2pt  ;
+
+    numeric text_offset         ; text_offset         := 4pt ;
+    numeric cell_offset         ; cell_offset         := 4pt ;
+
+    numeric line_distance       ; line_distance       := 10pt ; % between line and text
+    numeric line_offset         ; line_offset         :=  4pt ; % between center and start of line
+    numeric line_height         ; line_height         := 20pt ;
+
+    numeric cell_distance_y     ; cell_distance_y     := 20pt ;
+    numeric cell_distance_x     ; cell_distance_x     := 20pt ;
+
+    numeric text_distance_set   ; text_distance_set   :=  4pt ;
+
+    boolean chart_vertical      ; chart_vertical      := false ;
+
+    numeric nofcells            ; nofcells            := 0 ;
+
+enddef ;
+
+def step_cells (expr t, b) =
+    nofcells := nofcells + 1 ;
+    cells_t[nofcells] := textext.d(t) ;
+    cells_b[nofcells] := textext.d(b) ;
+    texts_t[nofcells] := nullpicture ;
+    texts_m[nofcells] := nullpicture ;
+    texts_b[nofcells] := nullpicture ;
+enddef ;
+
+def step_texts (expr t, b) =
+    texts_t[nofcells] := textext.d(t) ;
+    texts_m[nofcells] := textext.d(m) ;
+    texts_b[nofcells] := textext.d(b) ;
+enddef ;
+
+def step_begin_cell =
+    nofcells := nofcells + 1 ;
+    cells_t[nofcells] := nullpicture ;
+    cells_b[nofcells] := nullpicture ;
+    texts_t[nofcells] := nullpicture ;
+    texts_m[nofcells] := nullpicture ;
+    texts_b[nofcells] := nullpicture ;
+enddef ;
+
+def step_end_cell =
+enddef ;
+
+def step_cell_top (expr t) = cells_t[nofcells] := textext.d(t) ; enddef ;
+def step_cell_bot (expr b) = cells_b[nofcells] := textext.d(b) ; enddef ;
+def step_text_top (expr t) = texts_t[nofcells] := textext.d(t) ; enddef ;
+def step_text_mid (expr m) = texts_m[nofcells] := textext.d(m) ; enddef ;
+def step_text_bot (expr b) = texts_b[nofcells] := textext.d(b) ; enddef ;
+
+def step_begin_chart =
+    begingroup ;
+        initialize_step_variables ;
+        save nofcells ; numeric nofcells ; nofcells := 0 ;
+        save cells_t, cells_m, cells_b ; picture cells_t[], cells_m[], cells_b[] ;
+        save texts_t, texts_m, texts_b ; picture texts_t[], texts_m[], texts_b[] ;
+enddef ;
+
+def step_end_chart =
+    % we could combine some loops but this is cleaner
+    save dx, delta ; numeric dx, delta ;
+    save p ; path p ;
+    save one_row_only ; boolean one_row_only ;
+    save cell_t, next_t, text_t ; picture cell_t, next_t, text_t ;
+    save cell_m, next_m, text_m ; picture cell_m, next_m, text_m ;
+    save cell_b, next_b, text_b ; picture cell_b, next_b, text_b ;
+    save height_t, width_t, max_height_t, max_width_t ; numeric height_t, width_t, max_height_t, max_width_t ;
+    save height_m, width_m, max_height_m, max_width_m ; numeric height_m, width_m, max_height_m, max_width_m ;
+    save height_b, width_b, max_height_b, max_width_b ; numeric height_b, width_b, max_height_b, max_width_b ;
+    % check rows
+    one_row_only := true ;
+    for i=1 upto nofcells :
+        if bbwidth(cells_b[i]) > 0 :
+            one_row_only := false ;
+        fi ;
+    endfor ;
+    % swap and rotate
+    if chart_vertical :
+        if one_row_only :
+            % deal with mid_texts
+            max_width_t := max_width_m := max_width_b := 0 ;
+            for i=1 upto nofcells :
+                width_t := bbwidth(texts_t[i]) ;
+                width_m := bbwidth(texts_m[i]) ;
+                width_b := bbwidth(texts_b[i]) ;
+                if width_t > max_width_t : max_width_t := width_t fi ;
+                if width_m > max_width_m : max_width_m := width_m fi ;
+                if width_b > max_width_b : max_width_b := width_b fi ;
+            endfor ;
+            if max_width_m > 0 :
+                for i=1 upto nofcells :
+                    text_t := texts_t[i] ; width_t := bbwidth(text_t) ;
+                    text_m := texts_m[i] ; width_m := bbwidth(text_m) ;
+                    text_b := texts_b[i] ; width_b := bbwidth(text_b) ;
+                    if width_t < max_width_t :
+                        setbounds text_t to boundingbox text_t leftenlarged (max_width_t - width_t) ;
+                    fi ;
+                    if width_m < max_width_m :
+                        setbounds text_m to boundingbox text_m leftenlarged  ((max_width_m - width_m)/2) ;
+                        setbounds text_m to boundingbox text_m rightenlarged ((max_width_m - width_m)/2) ;
+                    fi ;
+                    if width_b < max_width_b :
+                        setbounds text_b to boundingbox text_b rightenlarged (max_width_b - width_b) ;
+                    fi ;
+                    text_t := text_t shifted (- xpart llcorner text_t, 0) ;
+                    text_m := text_m shifted (- xpart llcorner text_m, 0) ;
+                    text_b := text_b shifted (- xpart llcorner text_b, 0) ;
+                    texts_t[i] := image (
+                        draw text_t ;
+                        draw text_m shifted (max_width_t +                 text_distance_set,0) ;
+                        draw text_b shifted (max_width_t + max_width_m + 2*text_distance_set,0) ;
+                    ) rotated 90 ;
+                    texts_m[i] := texts_b[i] := nullpicture ;
+                    cells_t[i] := cells_t[i] rotated 90 ;
+                endfor ;
+            else :
+                for i=1 upto nofcells :
+                    cells_t[i] := cells_t[i] rotated 90 ;
+                    texts_t[i] := texts_t[i] rotated 90 ;
+                    texts_b[i] := texts_b[i] rotated 90 ;
+                endfor ;
+            fi ;
+        else :
+            for i=1 upto nofcells :
+                cell_t := cells_t[i] ;
+                cell_b := cells_b[i] ;
+                cells_t[i] := cell_b rotated 90 ;
+                cells_b[i] := cell_t rotated 90 ;
+                text_t := texts_t[i] ;
+                text_b := texts_b[i] ;
+                texts_t[i] := text_b rotated 90 ;
+                texts_b[i] := text_t rotated 90 ;
+            endfor ;
+        fi ;
+    fi ;
+    % align horizontal
+    for i=1 upto nofcells :
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        width_t := bbwidth(cell_t) ;
+        width_b := bbwidth(cell_b) ;
+        if (width_t = 0) and (width_b = 0) :
+            % skip
+        elseif (width_t > 0) and (width_t < width_b) :
+            delta := (width_b-width_t)/2 ;
+            setbounds cell_t to boundingbox cell_t leftenlarged delta rightenlarged delta ;
+            cells_t[i] := cell_t ;
+        elseif (width_b > 0) and (width_t > width_b) :
+            delta := (width_t-width_b)/2 ;
+            setbounds cell_b to boundingbox cell_b leftenlarged delta rightenlarged delta ;
+            cells_b[i] := cell_b ;
+        fi ;
+    endfor ;
+    % analyze vertical
+    max_height_t := 0 ;
+    max_height_b := 0 ;
+    for i=1 upto nofcells :
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        height_t := bbheight(cell_t) ;
+        height_b := bbheight(cell_b) ;
+        if height_t > 0 :
+            setbounds cell_t to boundingbox cell_t enlarged cell_offset ;
+            height_t := height_t + 2 * cell_offset ;
+            cells_t[i] := cell_t ;
+        fi ;
+        if height_b > 0 :
+            setbounds cell_b to boundingbox cell_b enlarged cell_offset ;
+            height_b := height_b + 2 * cell_offset ;
+            cells_b[i] := cell_b ;
+        fi ;
+        if height_t > max_height_t :
+            max_height_t := height_t ;
+        fi
+        if height_b > max_height_b :
+            max_height_b := height_b ;
+        fi ;
+    endfor ;
+    % align vertical
+    for i=1 upto nofcells :
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        height_t := bbheight(cell_t) ;
+        height_b := bbheight(cell_b) ;
+        if height_t > 0 :
+            delta := (max_height_t-height_t)/2 ;
+            setbounds cell_t to boundingbox cell_t topenlarged delta bottomenlarged delta ;
+        fi ;
+        if height_b > 0 :
+            delta := (max_height_b-height_b)/2 ;
+            setbounds cell_b to boundingbox cell_b topenlarged delta bottomenlarged delta ;
+        fi ;
+        cells_t[i] := cell_t ;
+        cells_b[i] := cell_b ;
+    endfor ;
+    % position
+    dx := 0 ;
+    for i=1 upto nofcells :
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        cell_t := cell_t shifted -llcorner cell_t ;
+        cell_b := cell_b shifted -llcorner cell_b ;
+        cell_t := cell_t shifted (dx, 0) ;
+        cell_b := cell_b shifted (dx,-cell_distance_y-max_height_b) ;
+        cells_t[i] := cell_t ;
+        cells_b[i] := cell_b ;
+        width_t := bbwidth(cell_t) ;
+        width_b := bbwidth(cell_b) ;
+        if width_t > 0 :
+            dx := dx + cell_distance_x + width_t ;
+        elseif width_b > 0 :
+            dx := dx + cell_distance_x + width_b ;
+        fi ;
+    endfor ;
+    % flush
+    for i=1 upto nofcells :
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        width_t := bbwidth(cell_t) ;
+        width_b := bbwidth(cell_b) ;
+        if width_t > 0 :
+            fill boundingbox cell_t withcolor cell_fill_color ;
+            draw boundingbox cell_t withpen pencircle scaled cell_line_width withcolor cell_line_color ;
+            draw cell_t ;
+        fi ;
+        if width_b > 0 :
+            fill boundingbox cell_b withcolor cell_fill_color ;
+            draw boundingbox cell_b withpen pencircle scaled cell_line_width withcolor cell_line_color ;
+            draw cell_b ;
+        fi ;
+    endfor ;
+    %
+    def midtopboundary    expr p = 0.5[ulcorner boundingbox p, urcorner boundingbox p] enddef ;
+    def midbottomboundary expr p = 0.5[llcorner boundingbox p, lrcorner boundingbox p] enddef ;
+    % draw top and bottom text boxes
+    for i=1 upto nofcells-1 :
+        text_t := texts_t[i] ;
+        text_b := texts_b[i] ;
+        if bbwidth(text_t) > 0 :
+            setbounds text_t to boundingbox text_t enlarged text_offset ;
+            texts_t[i] := text_t ;
+        fi ;
+        if bbwidth(text_b) > 0 :
+            setbounds text_b to boundingbox text_b enlarged text_offset ;
+            texts_b[i] := text_b ;
+        fi ;
+    endfor ;
+    % arrows
+    for i=1 upto nofcells-1 :
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        next_t := cells_t[i+1] ;
+        next_b := cells_b[i+1] ;
+        pair t_a, t_b, t_c, b_a, b_b, b_c ;
+        t_a := midtopboundary cell_t ;
+        t_b := midtopboundary next_t ;
+        t_c := (xpart 0.5[t_a,t_b], ypart t_a+line_height+line_distance) ;
+        if one_row_only :
+            b_a := midbottomboundary cell_t ;
+            b_b := midbottomboundary next_t ;
+        else :
+            b_a := midbottomboundary cell_b ;
+            b_b := midbottomboundary next_b ;
+        fi ;
+        b_c := (xpart 0.5[b_a,b_b], ypart b_a-line_height-line_distance) ;
+        texts_t[i] := thelabel.top(texts_t[i],t_c) ;
+        texts_b[i] := thelabel.bot(texts_b[i],b_c) ;
+    endfor ;
+    %
+    for i=1 upto nofcells-1 : % todo arrows when empty text
+        cell_t := cells_t[i] ;
+        cell_b := cells_b[i] ;
+        next_t := cells_t[i+1] ;
+        next_b := cells_b[i+1] ;
+        text_t := texts_t[i] ;
+        text_b := texts_b[i] ;
+        if bbwidth(text_t) > 0 :
+            if bbwidth(cell_t) > 0 :
+                drawarrow midtopboundary cell_t
+                    shifted (if i > 1 : line_offset else : 0 fi, cell_line_width) {up}  ..
+                    midbottomboundary text_t shifted (0,-line_distance) ..
+                    {down} midtopboundary next_t shifted(if i < nofcells - 1 : -line_offset else : 0 fi,cell_line_width)
+                    withpen pencircle scaled line_line_width
+                    withcolor line_line_color ;
+            else :
+            fi ;
+        fi ;
+        if bbwidth(text_b) > 0 :
+            if one_row_only :
+                cell_b := cell_t ;
+                next_b := next_t ;
+            fi ;
+            if bbwidth(cell_b) > 0 :
+                drawarrow midbottomboundary cell_b
+                    shifted (if i > 1 : line_offset else : 0 fi, -cell_line_width) {down}  ..
+                    midtopboundary text_b shifted (0, line_distance) ..
+                    {up} midbottomboundary next_b shifted (if i < nofcells - 1 : -line_offset else : 0 fi,-cell_line_width)
+                    withpen pencircle scaled line_line_width
+                    withcolor line_line_color ;
+            else :
+            fi ;
+        fi ;
+    endfor ;
+    % draw top and bottom text boxes
+    for i=1 upto nofcells-1 :
+        text_t := texts_t[i] ;
+        text_b := texts_b[i] ;
+        if bbwidth(text_t) > 0 :
+            fill boundingbox text_t withcolor text_fill_color ;
+            draw boundingbox text_t withpen pencircle scaled text_line_width withcolor text_line_color ;
+            draw text_t ;
+        fi ;
+        if bbwidth(text_b) > 0 :
+            fill boundingbox text_b withcolor text_fill_color ;
+            draw boundingbox text_b withpen pencircle scaled text_line_width withcolor text_line_color ;
+            draw text_b ;
+        fi ;
+    endfor ;
+    if chart_vertical :
+        % rotate back
+        currentpicture := currentpicture rotated -90 ;
+    fi ;
+    endgroup ;
+enddef ;
+
+% start_begin_step ;
+%     step_cells ("\strut test 0", "\strut test 0") ;
+%     step_cells ("\strut test 1", "\vbox{\hsize3cm \strut oeps 1\crlf oeps 1}") ;
+%     step_texts ("\strut 1",    "\strut 1") ;
+%     step_cells ("\strut test 2", "\strut oeps 2 oeps 2") ;
+%     step_cells ("\strut test X", "\strut test X") ;
+%     step_texts ("\strut 2",    "\strut 2") ;
+%     step_cells ("\strut test 3", "\strut oeps 3 oeps 3") ;
+%     step_texts ("\strut 3",    "\strut 3") ;
+%     step_cells ("\strut test 4", "\strut oeps 4 oeps 4") ;
+%     step_texts ("\strut 4",    "\strut 4") ;
+% stop_end_chart ;