Provided by: graphviz_2.40.1-6_amd64 bug

NAME

       dot - filter for drawing directed graphs
       neato - filter for drawing undirected graphs
       twopi - filter for radial layouts of graphs
       circo - filter for circular layout of graphs
       fdp - filter for drawing undirected graphs
       sfdp - filter for drawing large undirected graphs
       patchwork - filter for squarified tree maps
       osage - filter for array-based layouts

SYNOPSIS

       dot [options] [files]
       neato [options] [files]
       twopi [options] [files]
       circo [options] [files]
       fdp [options] [files]
       sfdp [options] [files]
       patchwork [options] [files]
       osage [options] [files]

DESCRIPTION

       These  are  a  collection of programs for drawing graphs.  There is actually only one main
       program; the specific layout algorithms are implemented as  plugins.  Thus,  they  largely
       share all of the same command-line options.

       dot draws directed graphs.  It works well on directed acyclic graphs and other graphs that
       can be drawn as hierarchies or have a natural ``flow.''

       neato draws undirected graphs using a ``spring'' model and  reducing  the  related  energy
       (see Kamada and Kawai, Information Processing Letters 31:1, April 1989).

       twopi  draws graphs using a radial layout (see G. Wills, Symposium on Graph Drawing GD'97,
       September, 1997).  Basically, one node is chosen as the center and put at the origin.  The
       remaining  nodes are placed on a sequence of concentric circles centered about the origin,
       each a fixed radial distance from the previous circle.  All  nodes  distance  1  from  the
       center  are  placed  on  the  first  circle; all nodes distance 1 from a node on the first
       circle are placed on the second circle; and so forth.

       circo draws graphs using a circular layout (see Six and Tollis, GD '99 and ALENEX '99, and
       Kaufmann  and  Wiese,  GD  '02.)  The tool identifies biconnected components and draws the
       nodes of the component on a circle. The block‐cutpoint tree  is  then  laid  out  using  a
       recursive  radial  algorithm.  Edge  crossings within a circle are minimized by placing as
       many edges on the circle's perimeter as possible.  In  particular,  if  the  component  is
       outerplanar,  the component will have a planar layout.  If a node belongs to multiple non‐
       trivial biconnected components, the layout puts the node in one of them. By default,  this
       is the first non‐trivial component found in the search from the root component.

       fdp  draws  undirected  graphs  using  a  ``spring''  model. It relies on a force‐directed
       approach in the spirit of Fruchterman and Reingold  (cf.  Software‐Practice  &  Experience
       21(11), 1991, pp. 1129‐1164).

       sfdp  also draws undirected graphs using the ``spring'' model described above, but it uses
       a multi-scale approach to produce layouts of large graphs in a reasonably short time.

       patchwork draws the graph as a squarified treemap  (see  M.  Bruls  et  al.,  ``Squarified
       treemaps'',  Proc.  Joint  Eurographics  and  IEEE  TCVG Symp. on Visualization, 2000, pp.
       33-42). The clusters of the graph are used to specify the tree.

       osage draws the graph using its cluster structure.  For  a  given  cluster,  each  of  its
       subclusters  is  laid out internally.  Then the subclusters, plus any remaining nodes, are
       repositioned based on the cluster's pack and packmode attributes.

OUTPUT FORMATS

       Graphviz uses an extensible plugin mechanism for its output  renderers,  so  to  see  what
       output  formats  your  installation  of dot supports you can use ``dot -T:'' and check the
       warning message.  Also, The plugin mechanism  supports  multiple  implementations  of  the
       output formats, allowing variations in the renderers and formatters.  To see what variants
       are available for a particular output format, use, for  example:  ``dot  -Tpng:''  and  to
       force a particular variant, use, for example: ``dot -Tpng:gd''

       Traditionally, Graphviz supports the following:
       -Tdot (Dot format containing layout infomation),
       -Txdot (Dot format containing complete layout infomation),
       -Tps (PostScript),
       -Tpdf (PDF),
       -Tsvg -Tsvgz (Structured Vector Graphics),
       -Tfig (XFIG graphics),
       -Tpng (png bitmap graphics),
       -Tgif (gif bitmap graphics),
       -Tjpg -Tjpeg (jpeg bitmap graphics),
       -Tjson (xdot information encoded in JSON),
       -Timap  (imagemap  files  for httpd servers for each node or edge that has a non‐null href
       attribute.),
       -Tcmapx (client‐side imagemap for use in html and xhtml).
       Additional  less  common  or  more  special‐purpose  output  formats  can  be   found   at
       //http://www.graphviz.org/content/output-formats.

       Alternative  plugins  providing  support  for  a given output format can be found from the
       error message resulting from appending a ':' to the format. e.g. -Tpng: The  first  plugin
       listed is always the default.

       The  -P  switch can be used to produce a graph of all output variants supported by plugins
       in the local installation of graphviz.

GRAPH FILE LANGUAGE

       Here is a synopsis of the graph file language,  normally  using  the  extension  .gv,  for
       graphs:

       [strict] (graph|digraph) name { statement‐list }
       is  the  top‐level  graph.  If  the  graph  is strict, then multiple edges are not allowed
       between the same pairs of nodes.  If it is a directed graph, indicated  by  digraph,  then
       the edgeop must be "->". If it is an undirected graph then the edgeop must be "--".

       Statements may be:

       name=val;
       node [name=val];
       edge [name=val];
       Set  default  graph,  node,  or  edge  attribute name to val.  Any subgraph, node, or edge
       appearing after this inherits the new default attributes.

       n0 [name0=val0,name1=val1,...];
       Creates node n0 (if it does not already exist) and sets its attributes  according  to  the
       optional list.

       n0 edgeop n1 edgeop ... edgeop nn [name0=val0,name1=val1,...];
       Creates  edges  between  nodes  n0, n1, ..., nn and sets their attributes according to the
       optional list.  Creates nodes as necessary.

       [subgraph name] { statement‐list }
       Creates a subgraph.  Subgraphs may be used in place of n0, ..., nn in the above statements
       to  create  edges.   [subgraph  name] is optional; if missing, the subgraph is assigned an
       internal name.

       The language accepts both C‐style comments /*C...*/ or //...

       Attribute names and  values  are  ordinary  (C‐style)  strings.   The  following  sections
       describe attributes that control graph layout.

       A     more    complete    description    of    the    language    can    be    found    at
       http://www.graphviz.org/content/dot-language.

GRAPH, NODE AND EDGE ATTRIBUTES

       Graphviz uses the name=value attributes, attached to graphs, subgraphs, nodes  and  edges,
       to  tailor  the  layout  and  rendering.  We list the more prominent attributes below. The
       complete list is available at http://www.graphviz.org/content/attrs.

  Attributes Common to Nodes, Edges, Clusters and Graphs
       href=url the default url for image map files; in PostScript files, the base  URL  for  all
       relative URLs, as recognized by Acrobat Distiller 3.0 and up.

       URL=url (``URL'' is a synonym for ``href.'')

       fontcolor=colorvalue sets the label text color.

       A colorvalue may be "h,s,v" (hue, saturation, brightness) floating point numbers between 0
       and 1, or an X11 color name such as white, black, red, green, blue,  yellow,  magenta,  or
       cyan,   or   a   "#rrggbb"   (red,  green,  blue,  2  hex  characters  each)  value.   See
       http://www.graphviz.org/content/attrs#kcolor  and   http://www.graphviz.org/content/color-
       names for further details.

       fontsize=n sets the label type size to n points.

       fontname=name sets the label font family name.

       label=text  where  text  may  include escaped newlines \n, \l, or \r for center, left, and
       right justified lines.  The string '\G' value will be replaced by  the  graph  name.   For
       node  labels,  the string '\N' value will be replaced by the node name.  For edges, if the
       substring '\T' is found in a label, it will be replaced by the name of the tail  node;  if
       the  substring '\H' is found in a label, it will be replaced by the name of the head node;
       if  the  substring  '\E'  value  is  found  in  a  label   it   will   be   replaced   by:
       tail_node_name->head_node_name   or   by:  tail_node_name--head_node_name  for  undirected
       graphs.

       Graphviz also supports special HTML-like labels for constructing complex node  content.  A
       full‐description of these is given at http://www.graphviz.org/content/node-shapes#html.

       If  a node has shape=record, the label may contain recursive box lists delimited by { | }.
       Port identifiers in labels are set off by angle brackets < >.

  Graph Attributes
       size="x,y" specifies the maximum bounding box of drawing in inches.

       ratio=f sets the aspect ratio to f which may be a floating point number,  or  one  of  the
       keywords fill, compress, or auto.

       layout=engine indicates the preferred layout engine (dot, neato, fdp, etc.) overriding the
       default from the basename of the command or the -K commandline option.

       margin=f sets the page margin (included in the page size).

       ordering=out constrains order of out‐edges in a subgraph according to their file sequence.

       rotate=90 sets landscape mode.  (orientation=land is backward compatible but obsolete.)

       center=n a non‐zero value centers the drawing on the page.

       color=colorvalue sets foreground color (bgcolor for background).

       overlap=mode. This specifies what algorithm should do if any nodes  overlap.  If  mode  is
       false,  the program uses the Prism algorithm to adjust the nodes to eliminate overlaps. If
       mode is scale, the layout is uniformly scaled up, preserving node sizes,  until  nodes  no
       longer  overlap.  The  latter  technique  removes  overlaps  while preserving symmetry and
       structure, while the former removes overlaps more compactly but destroys  symmetries.   If
       mode  is  true  (the  default),  no repositioning is done.  Since the dot algorithm always
       produces a layout with no node overlaps, this attribute is only useful with other layouts.

       stylesheet="file.css" includes a reference to a stylesheet in -Tsvg  and  -Tsvgz  outputs.
       Ignored by other formats.

       splines  If  set to true, edges are drawn as splines.  If set to polyline, edges are drawn
       as polylines.  If set to ortho, edges are drawn as orthogonal polylines.  In all of  these
       cases,  the  nodes must not overlap.  If splines=false or splines=line, edges are drawn as
       line segments.  The default is true for dot, and false for all other layouts.

       (dot‐specific attributes)

       nodesep=f sets the minimum separation between nodes.

       ranksep=f sets the minimum separation between ranks.

       rankdir=LR|RL|BT requests a left‐to‐right, right‐to‐left, or bottom‐to‐top, drawing.

       rank=same (or min or max) in a subgraph constrains the rank assignment of its nodes.    If
       a  subgraph's  name has the prefix cluster, its nodes are drawn in a distinct rectangle of
       the layout.  Clusters may be nested.

       (neato‐specific attributes)
       mode=val.  Algorithm for minimizing energy in the layout. By default,  neato  uses  stress
       majorization. If mode=KK, it uses a version of gradient descent.

       model=val.   The neato model computes the desired distances between all pairs of vertices.
       By default, it uses the length of the shortest  path.  If  model  is  set  to  circuit,  a
       circuit-resistance  model is used.  If model is set to subset, it uses a model whereby the
       edge length is the number of nodes that  are  neighbors  of  exactly  one  of  the  edge's
       vertices.

       start=val.   Requests  random initial placement and seeds the random number generator.  If
       val is not an integer, the process ID or current time is used as the seed.

       epsilon=n.  Sets the cutoff for the solver.  The default is 0.1.

       (twopi‐specific attributes)
       root=ctr. This specifies the node to  be  used  as  the  center  of  the  layout.  If  not
       specified,  twopi  will randomly pick one of the nodes that are furthest from a leaf node,
       where a leaf node is a node of degree 1. If no leaf nodes exists,  an  arbitrary  node  is
       picked as center.

       ranksep=val.  Specifies  the  radial distance in inches between the sequence of rings. The
       default is 0.75.

       (circo‐specific attributes)
       root=nodename. Specifies the name of a node occurring in the root block. If the  graph  is
       disconnected, the root node attribute can be used to specify additional root blocks.

       mindist=value.  Sets the minimum separation between all nodes. If not specified then circo
       uses a default value of 1.0.

       (fdp‐specific attributes)
       K=val. Sets the default ideal node separation in the layout.

       maxiter=val. Sets the maximum number of iterations used to layout the graph.

       start=val. Adjusts the random initial placement of nodes with no specified  position.   If
       val  is  is an integer, it is used as the seed for the random number generator.  If val is
       not an integer, a random system‐generated integer, such as the process ID or current time,
       is used as the seed.

  Node Attributes
       height=d  or  width=d sets minimum height or width.  Adding fixedsize=true forces these to
       be the actual size (text labels are ignored).

       shape=builtin_polygon record epsf
       builtin_polygon can be such values as plaintext, ellipse,  oval,  circle,  egg,  triangle,
       box,  diamond,  trapezium,  parallelogram,  house,  hexagon, octagon, note, tab, box3d, or
       component,, among others.  (Polygons  are  defined  or  modified  by  the  following  node
       attributes: regular, peripheries, sides, orientation, distortion and skew.)  epsf uses the
       node's shapefile attribute as the path name of an external EPSF file to  be  automatically
       loaded for the node shape.

       See http://www.graphviz.org/content/node-shapes for a complete description of node shapes.

       color=colorvalue  sets  the  outline color, and the default fill color if style=filled and
       fillcolor is not specified.

       fillcolor=colorvalue sets the  fill  color  when  style=filled.   If  not  specified,  the
       fillcolor when style=filled defaults to be the same as the outline color.

       style=filled solid dashed dotted bold invis

       xlabel="text"  specifies  a  label  that  will  be place near, but outside, of a node. The
       normal label string is placed within the node shape.

       target="target" is a target string for client‐side imagemaps and SVG, effective when nodes
       have  a  URL.   The target string is used to determine which window of the browser is used
       for the URL.  Setting it to "_graphviz" will open a  new  window  if  it  doesn't  already
       exist, or reuse it if it does.  If the target string is empty, the default, then no target
       attribute is included in the output.  The substrings '\N' and '\G' are substituted in  the
       same  manner  as  for  the  node  label  attribute.   Additionally  the  substring '\L' is
       substituted with the node label string.

       tooltip="text" is a tooltip string for client‐side imagemaps and SVG, effective when nodes
       have  a  URL.   The  tooltip  string defaults to be the same as the label string, but this
       attribute permits nodes without labels to  still  have  tooltips  thus  permitting  denser
       graphs.   The  substrings '\N' and '\G' are substituted in the same manner as for the node
       label attribute.  Additionally the substring '\L'  is  substituted  with  the  node  label
       string.

       The following attributes apply only to polygon shape nodes:

       regular=n  if  n  is non‐zero then the polygon is made regular, i.e. symmetric about the x
       and  y  axis,  otherwise  the  polygon  takes  on  the  aspect   ratio   of   the   label.
       builtin_polygons  that  are  not  already  regular  are  made  regular  by this attribute.
       builtin_polygons that are already regular are not affected  (i.e.   they  cannot  be  made
       asymmetric).

       peripheries=n  sets  the  number  of periphery lines drawn around the polygon.  This value
       supersedes the number of periphery lines of builtin_polygons.

       sides=n sets the number of sides  to  the  polygon.  n<3  results  in  an  ellipse.   This
       attribute is ignored by builtin_polygons.

       orientation=f  sets the orientation of the first apex of the polygon counterclockwise from
       the vertical, in degrees.  f may be a floating point number.  The orientation of labels is
       not  affected  by  this  attribute.  This attribute is added to the initial orientation of
       builtin_polygons.

       distortion=f sets the amount of broadening of the top and narrowing of the bottom  of  the
       polygon  (relative  to  its  orientation).   Floating  point  values between -1 and +1 are
       suggested.  This attribute is ignored by builtin_polygons.

       skew=f sets the amount of right‐displacement of  the  top  and  left‐displacement  of  the
       bottom of the polygon (relative to its orientation).  Floating point values between -1 and
       +1 are suggested.  This attribute is ignored by builtin_polygons.

       (circo‐specific attributes)
       root=true/false. This specifies that the block containing the given node be treated as the
       root of the spanning tree in the layout.

       (neato‐ and fdp‐specific attributes)
       pin=val. If val is true, the node will remain at its initial position.

  Edge Attributes
       weight=val  where  val  is  the  cost  of the edge.  For dot, weights must be non-negative
       integers.  Values greater than 1 tend to shorten  the  edge;   weight  0  flat  edges  are
       ignored  for ordering nodes.  In twopi, a weight of 0 will cause the edge to be ignored in
       constructing the underlying spanning tree. For neato and fdp, a heavier  weight  will  put
       more  emphasis  on  the algorithm achieving an edge length closer to that specified by the
       edge's len attribute.

       style=solid dashed dotted bold invis

       color=colorvalue sets the line color for edges.

       color=colorvaluelist a ':' separated list of colorvalue creates parallel edges,  one  edge
       for each color.

       dir=forward back both none controls arrow direction.

       tailclip,headclip=false disables endpoint shape clipping.

       target="text"  is  a target string for client‐side imagemaps and SVG, effective when edges
       have a URL.  If the target string is empty, the  default,  then  no  target  attribute  is
       included  in  the output.  The substrings '\T', '\H', '\E' and '\G' are substituted in the
       same manner as  for  the  edge  label  attribute.   Additionally  the  substring  '\L'  is
       substituted with the edge label string.

       tooltip="text"  is  a tooltip string for client‐side imagemaps effective when edges have a
       URL.  The tooltip string defaults to be the same as the edge label string.  The substrings
       '\T',  '\H',  '\E'  and  '\G'  are  substituted  in  the same manner as for the edge label
       attribute.  Additionally the substring '\L' is substituted with the edge label string.

       arrowhead,arrowtail=none, normal, inv, dot, odot, invdot, invodot, tee,  empty,  invempty,
       open,  halfopen,  diamond,  odiamond,  box,  obox, crow.  Specifies the shape of the glyph
       occurring where the edge touches the head or tail node, respectively. Note that this  only
       specifies the shape. The dir attribute determines whether or not the glyph is drawn.

       arrowsize=val  specifies  a  multiplicative  scale  factor  for the size of the arrowhead.
       inv_length=6,inv_width=7,dot_radius=2)

       headlabel,taillabel=text for labels appearing near the head and tail  nodes  of  an  edge.
       labelfontcolor,  labelfontname,  labelfontsize  for  head and tail labels.  The substrings
       '\T', '\H', '\E' and '\G' are substituted in  the  same  manner  as  for  the  edge  label
       attribute.  Additionally the substring '\L' is substituted with the edge label string.

       headhref="url"  sets the url for the head port in imagemap, PostScript and SVG files.  The
       substrings '\T', '\H', '\E' and '\G' are substituted in the same manner as  for  the  edge
       label  attribute.   Additionally  the  substring  '\L'  is substituted with the edge label
       string.

       headURL="url" (headURL is a synonym for headhref.)

       headtarget="headtarget" is a target string for client‐side imagemaps  and  SVG,  effective
       when  edge  heads  have a URL.  The headtarget string is used to determine which window of
       the browser is used for the URL.  If the headtarget string is  empty,  the  default,  then
       headtarget  defaults to the same value as target for the edge.  The substrings '\T', '\H',
       '\E' and '\G' are substituted in  the  same  manner  as  for  the  edge  label  attribute.
       Additionally the substring '\L' is substituted with the edge label string.

       headtooltip="tooltip"  is  a  tooltip string for client‐side imagemaps effective when head
       ports have a URL.  The tooltip string defaults to be the same  as  the  headlabel  string.
       The  substrings  '\T',  '\H',  and '\E' are substituted in the same manner as for the edge
       label attribute.  Additionally the substring '\L'  is  substituted  with  the  edge  label
       string.

       tailhref="url"  sets the url for the tail port in imagemap, PostScript and SVG files.  The
       substrings '\T', '\H', '\E' and '\G' are substituted in the same manner as  for  the  edge
       label  attribute.   Additionally  the  substring  '\L'  is substituted with the edge label
       string.

       tailURL="url" (tailURL is a synonym for tailhref.)

       tailtarget="tailtarget" is a target string for client‐side imagemaps  and  SVG,  effective
       when  edge  tails  have a URL.  The tailtarget string is used to determine which window of
       the browser is used for the URL.  If the tailtarget string is  empty,  the  default,  then
       tailtarget  defaults to the same value as target for the edge.  The substrings '\T', '\H',
       '\E' and '\G' are substituted in  the  same  manner  as  for  the  edge  label  attribute.
       Additionally the substring '\L' is substituted with the edge label string.

       tailtooltip="tooltip"  is  a  tooltip string for client‐side imagemaps effective when tail
       ports have a URL.  The tooltip string defaults to be the same  as  the  taillabel  string.
       The  substrings  '\T',  '\H',  '\E' and '\G' are substituted in the same manner as for the
       edge label attribute.  Additionally the substring '\L' is substituted with the edge  label
       string.

       labeldistance  and  labelangle  (in  degrees  CCW)  specify the placement of head and tail
       labels.

       decorate draws line from edge to label.

       samehead,sametail aim edges having the same value to the  same  port,  using  the  average
       landing point.

       (dot‐specific attributes)
       constraint=false causes an edge to be ignored for rank assignment.

       minlen=n  where  n  is an integer factor that applies to the edge length (ranks for normal
       edges, or minimum node separation for flat edges).

       xlabel="text" Edge labels in dot are  treated  as  special  types  of  nodes,  with  space
       allocated  for  them during node layout. This can sometimes deform the edge routing. If an
       xlabel is used instead,  the  label  is  placed  after  all  nodes  and  edges  have  been
       positioned. In turn, this may mean that there is some overlap among the labels.

       (neato and fdp‐specific attributes)
       len=f sets the optimal length of an edge.  The default is 1.0.

COMMAND‐LINE OPTIONS

       -G sets a default graph attribute.
       -N sets a default node attribute.
       -E sets a default edge attribute.  Example: -Gsize="7,8" -Nshape=box -Efontsize=8

       -lfile  loads  custom  PostScript  library  files.   Usually these define custom shapes or
       styles.  If -l is given by itself, the standard library is omitted.

       -Tlang sets the output language as described above.

       -n[1|2] (no‐op) If set, neato assumes nodes have already been  positioned  and  all  nodes
       have  a  pos  attribute  giving the positions.  It then performs an optional adjustment to
       remove node‐node overlap, depending on the value of the overlap  attribute,  computes  the
       edge  layouts, depending on the value of the splines attribute, and emits the graph in the
       appropriate format.  If num is supplied, the following actions occur:
           num = 1
       Equivalent to -n.
           num > 1
       Use node positions as specified, with no adjustment to remove node‐node overlaps, and  use
       any  edge  layouts  already specified by the pos attribute.  neato computes an edge layout
       for any edge that does not have a pos attribute.  As usual, edge layout is guided  by  the
       splines attribute.

       -Klayout override the default layout engine implied by the command name.

       -O automatically generate output filenames based on the input filename and the -T format.

       -P generate a graph of the currently available plugins.

       -v (verbose) prints various information useful for debugging.

       -c configure plugins.

       -m memory test (observe no growth with top, kill when done).

       -qlevel set level of message suppression. The default is 1.

       -sfscale scale input by fscale, the default is 72.

       -y invert y coordinate in output.

       -V (version) prints version information and exits.

       -? prints the usage and exits.

       A   complete   description   of  the  available  command‐line  options  can  be  found  at
       http://www.graphviz.org/content/command-line-invocation.

EXAMPLES

       digraph test123 {
               a -> b -> c;
               a -> {x y};
               b [shape=box];
               c [label="hello\nworld",color=blue,fontsize=24,
                    fontname="Palatino-Italic",fontcolor=red,style=filled];
               a -> z [label="hi", weight=100];
               x -> z [label="multi-line\nlabel"];
               edge [style=dashed,color=red];
               b -> x;
               {rank=same; b x}
       }

       graph test123 {
               a -- b -- c;
               a -- {x y};
               x -- c [w=10.0];
               x -- y [w=5.0,len=3];
       }

CAVEATS

       Edge splines can overlap unintentionally.

       Flat edge labels are slightly broken.  Intercluster edge labels are totally broken.

       Because unconstrained optimization is employed, node boxes can possibly overlap  or  touch
       unrelated edges.  All existing spring embedders seem to have this limitation.

       Apparently  reasonable  attempts to pin nodes or adjust edge lengths and weights can cause
       instability.

AUTHORS

       Stephen C. North <north@research.att.com>
       Emden R. Gansner <erg@graphviz.org>
       John C. Ellson <ellson@research.att.com>
       Yifan Hu <yifanhu@yahoo.com>

       The bitmap driver (PNG, GIF etc) is by Thomas Boutell, <http://www.boutell.com/gd>

       The Truetype font renderer is from the Freetype Project (David Turner, Robert Wilhelm, and
       Werner Lemberg) (who can be contacted at freetype-devel@lists.lrz-muenchen.de).

SEE ALSO

       This  man  page  contains  only  a small amount of the information related to the Graphviz
       layout    programs.    The    most    complete    information    can    be    found     at
       http://www.graphviz.org/Documentation.php, especially in the on‐line reference pages. Most
       of these documents are also available in the doc and doc/info subtrees in the  source  and
       binary distributions.

       dotty(1),tcldot(n),xcolors(1),libgraph(3).

       E. R. Gansner, S. C. North,  K. P. Vo, "DAG ‐ A Program to Draw Directed Graphs", Software
       ‐ Practice and Experience 17(1), 1988, pp. 1047‐1062.
       E. R. Gansner, E. Koutsofios, S. C. North,  K. P. Vo, "A Technique  for  Drawing  Directed
       Graphs," IEEE Trans. on Soft. Eng. 19(3), 1993, pp. 214‐230.
       S.  North and E. Koutsofios, "Applications of graph visualization", Graphics Interface 94,
       pp. 234‐245.
       E. R. Gansner and E. Koutsofios and S. C. North, "Drawing Graphs with dot,"  Available  at
       http://www.graphviz.org/pdf/dotguide.pdf.
       S. C. North, "NEATO User's Manual".  Available http://www.graphviz.org/pdf/neatoguide.pdf.
       E.  R. Gansner and Y. Hu, "Efficient, Proximity-Preserving Node Overlap Removal", J. Graph
       Algorithms Appl., 14(1) pp. 53‐74, 2010.

                                         12 January 2015                                   DOT(1)