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author	wolffd
date	Tue, 10 Feb 2015 15:05:51 +0000
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+:e9a9cd732c1e
+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<!--
+This is a generated document.  Do not edit.
+-->
+<HTML VERSION="2.0">
+<HEAD>
+<TITLE>Node, Edge and Graph Attributes</TITLE>
+</HEAD>
+<BODY BGCOLOR=white>
+<A NAME="top"></A>
+<H1 align=CENTER>Node, Edge and Graph Attributes</H1>
+<HR>
+The table below describes the attributes used by various Graphviz tools.
+The table gives the name of the attribute, the graph components (node,
+edge, etc.) which use the attribute and the type of the attribute
+(strings representing legal values of that type). Where applicable, the table
+also gives a default value for the attribute, a minimum allowed setting
+for numeric attributes, and certain restrictions on the use of the attribute.
+<P>
+All Graphviz attributes are specified by name-value pairs. Thus, to
+set the fillcolor of a node <TT>abc</TT>, one would use
+<TABLE>
+<TR><TD><TT>abc [fillcolor = red]</TT></TR>
+</TABLE>
+Similarly, to set the arrowhead style of an edge <TT>abc -> def</TT>,
+one would use
+<TABLE>
+<TR><TD><TT>abc -> def [arrowhead = diamond]</TT></TR>
+</TABLE>
+Further details concerning the setting of attributes can be found
+in the description of the
+<A HREF="http://www.graphviz.org/doc/info/lang.html">DOT language.</A>
+<P>
+At present, most device-independent units are either inches or
+<A NAME="points"></A>
+<A HREF="http://en.wikipedia.org/wiki/Point_(typography)">points</A>,
+which we take as 72 points per inch.
+<P>
+<A NAME=h:undir_note><STRONG>Note:</STRONG></A> Some attributes, such as
+<A HREF=#d:dir>dir</A> or <A HREF=#d:arrowtail>arrowtail</A>, are
+ambiguous when used in
+<A HREF="http://www.graphviz.org/doc/info/lang.html">DOT</A>
+with an undirected graph since the head and tail of an edge are meaningless.
+As a convention, the first time an undirected edge appears, the
+<A HREF="http://www.graphviz.org/doc/info/lang.html">DOT</A>
+parser will assign the left node as the tail node and the right node as
+the head. For example, the edge <TT>A -- B</TT> will have tail <TT>A</TT>
+and head <TT>B</TT>. It is the user's responsibility to handle such
+edges consistently. If the edge appears later, in the format
+<TABLE>
+<TR><TD><TT>B -- A [taillabel = "tail"]</TT></TR>
+</TABLE>
+the drawing will attach the tail label to node <TT>A</TT>.
+To avoid possible confusion when such attributes are required, the user
+is encouraged to use a directed graph.
+If it is important to make the graph appear undirected, this can be
+done using the <A HREF=#d:dir>dir</A>, <A HREF=#d:arrowtail>arrowtail</A>
+or <A HREF=#d:arrowhead>arrowhead</A> attributes.
+<P>
+The tools accept standard C representations for <EM>int</EM> and
+<EM>double</EM> types.
+For the <A NAME=k:bool><EM>bool</EM></A> type, TRUE values are
+represented by "true" (case-insensitive)
+and any non-zero integer, and FALSE values by "false" (case-insensitive)
+and zero.
+In addition, there are a variety of specialized types such as
+<EM>arrowType</EM>, <EM>color</EM>,
+<EM>pointf</EM> and <EM>rankdir</EM>. Legal values for these types are given
+at the end.
+<P>
+In the <A NAME=h:uses><STRONG>Used By</STRONG></A> field, the
+characters E, N, G, S and C
+represent edges, nodes, the root graph, subgraphs
+and cluster subgraphs, respectively.
+This field indicates which graph component uses the attribute.
+<HR ALIGN=CENTER WIDTH="70%" SIZE=3>
+<TABLE ALIGN=CENTER>
+<TR><TH>Name</TH><TH><A HREF=#h:uses>Used By</A></TH><TH>Type</TH><TH>Default</TH><TH>Minimum</TH><TH>Notes</TH></TR>
+<TR><TD><A NAME=a:Damping HREF=#d:Damping>Damping</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">0.99</TD><TD>0.0</TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:K HREF=#d:K>K</A>
+</TD><TD>GC</TD><TD>double</TD><TD ALIGN="CENTER">0.3</TD><TD>0</TD><TD>sfdp, fdp only</TD> </TR>
+<TR><TD><A NAME=a:URL HREF=#d:URL>URL</A>
+</TD><TD>ENGC</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD>svg, postscript, map only</TD> </TR>
+<TR><TD><A NAME=a:arrowhead HREF=#d:arrowhead>arrowhead</A>
+</TD><TD>E</TD><TD><A HREF=#k:arrowType>arrowType</A>
+</TD><TD ALIGN="CENTER">normal</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:arrowsize HREF=#d:arrowsize>arrowsize</A>
+</TD><TD>E</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD>0.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:arrowtail HREF=#d:arrowtail>arrowtail</A>
+</TD><TD>E</TD><TD><A HREF=#k:arrowType>arrowType</A>
+</TD><TD ALIGN="CENTER">normal</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:aspect HREF=#d:aspect>aspect</A>
+</TD><TD>G</TD><TD><A HREF=#k:aspectType>aspectType</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:bb HREF=#d:bb>bb</A>
+</TD><TD>G</TD><TD><A HREF=#k:rect>rect</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>write only</TD> </TR>
+<TR><TD><A NAME=a:bgcolor HREF=#d:bgcolor>bgcolor</A>
+</TD><TD>GC</TD><TD><A HREF=#k:color>color</A>
+</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:center HREF=#d:center>center</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:charset HREF=#d:charset>charset</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">"UTF-8"</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:clusterrank HREF=#d:clusterrank>clusterrank</A>
+</TD><TD>G</TD><TD><A HREF=#k:clusterMode>clusterMode</A>
+</TD><TD ALIGN="CENTER">local</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:color HREF=#d:color>color</A>
+</TD><TD>ENC</TD><TD><A HREF=#k:color>color</A>
+<BR><A HREF=#k:colorList>colorList</A>
+</TD><TD ALIGN="CENTER">black</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:colorscheme HREF=#d:colorscheme>colorscheme</A>
+</TD><TD>ENCG</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:comment HREF=#d:comment>comment</A>
+</TD><TD>ENG</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:compound HREF=#d:compound>compound</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:concentrate HREF=#d:concentrate>concentrate</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:constraint HREF=#d:constraint>constraint</A>
+</TD><TD>E</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">true</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:decorate HREF=#d:decorate>decorate</A>
+</TD><TD>E</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:defaultdist HREF=#d:defaultdist>defaultdist</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">1+(avg. len)*sqrt(|V|)</TD><TD>epsilon</TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:dim HREF=#d:dim>dim</A>
+</TD><TD>G</TD><TD>int</TD><TD ALIGN="CENTER">2</TD><TD>2</TD><TD>sfdp, fdp, neato only</TD> </TR>
+<TR><TD><A NAME=a:dimen HREF=#d:dimen>dimen</A>
+</TD><TD>G</TD><TD>int</TD><TD ALIGN="CENTER">2</TD><TD>2</TD><TD>sfdp, fdp, neato only</TD> </TR>
+<TR><TD><A NAME=a:dir HREF=#d:dir>dir</A>
+</TD><TD>E</TD><TD><A HREF=#k:dirType>dirType</A>
+</TD><TD ALIGN="CENTER">forward(directed)<BR>none(undirected)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:diredgeconstraints HREF=#d:diredgeconstraints>diredgeconstraints</A>
+</TD><TD>G</TD><TD>string<BR><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:distortion HREF=#d:distortion>distortion</A>
+</TD><TD>N</TD><TD>double</TD><TD ALIGN="CENTER">0.0</TD><TD>-100.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:dpi HREF=#d:dpi>dpi</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">96.0<BR>0.0</TD><TD></TD><TD>svg, bitmap output only</TD> </TR>
+<TR><TD><A NAME=a:edgeURL HREF=#d:edgeURL>edgeURL</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:edgehref HREF=#d:edgehref>edgehref</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:edgetarget HREF=#d:edgetarget>edgetarget</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:edgetooltip HREF=#d:edgetooltip>edgetooltip</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, cmap only</TD> </TR>
+<TR><TD><A NAME=a:epsilon HREF=#d:epsilon>epsilon</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">.0001 * # nodes(mode == KK)<BR>.0001(mode == major)</TD><TD></TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:esep HREF=#d:esep>esep</A>
+</TD><TD>G</TD><TD>double<BR><A HREF=#k:pointf>pointf</A>
+</TD><TD ALIGN="CENTER">+3</TD><TD></TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:fillcolor HREF=#d:fillcolor>fillcolor</A>
+</TD><TD>NC</TD><TD><A HREF=#k:color>color</A>
+</TD><TD ALIGN="CENTER">lightgrey(nodes)<BR>black(clusters)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:fixedsize HREF=#d:fixedsize>fixedsize</A>
+</TD><TD>N</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:fontcolor HREF=#d:fontcolor>fontcolor</A>
+</TD><TD>ENGC</TD><TD><A HREF=#k:color>color</A>
+</TD><TD ALIGN="CENTER">black</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:fontname HREF=#d:fontname>fontname</A>
+</TD><TD>ENGC</TD><TD>string</TD><TD ALIGN="CENTER">"Times-Roman"</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:fontnames HREF=#d:fontnames>fontnames</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg only</TD> </TR>
+<TR><TD><A NAME=a:fontpath HREF=#d:fontpath>fontpath</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">system-dependent</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:fontsize HREF=#d:fontsize>fontsize</A>
+</TD><TD>ENGC</TD><TD>double</TD><TD ALIGN="CENTER">14.0</TD><TD>1.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:group HREF=#d:group>group</A>
+</TD><TD>N</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:headURL HREF=#d:headURL>headURL</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:headclip HREF=#d:headclip>headclip</A>
+</TD><TD>E</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">true</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:headhref HREF=#d:headhref>headhref</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:headlabel HREF=#d:headlabel>headlabel</A>
+</TD><TD>E</TD><TD><A HREF=#k:lblString>lblString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:headport HREF=#d:headport>headport</A>
+</TD><TD>E</TD><TD><A HREF=#k:portPos>portPos</A>
+</TD><TD ALIGN="CENTER">center</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:headtarget HREF=#d:headtarget>headtarget</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:headtooltip HREF=#d:headtooltip>headtooltip</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, cmap only</TD> </TR>
+<TR><TD><A NAME=a:height HREF=#d:height>height</A>
+</TD><TD>N</TD><TD>double</TD><TD ALIGN="CENTER">0.5</TD><TD>0.02</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:href HREF=#d:href>href</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, postscript, map only</TD> </TR>
+<TR><TD><A NAME=a:id HREF=#d:id>id</A>
+</TD><TD>GNE</TD><TD><A HREF=#k:lblString>lblString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, postscript, map only</TD> </TR>
+<TR><TD><A NAME=a:image HREF=#d:image>image</A>
+</TD><TD>N</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:imagescale HREF=#d:imagescale>imagescale</A>
+</TD><TD>N</TD><TD><A HREF=#k:bool>bool</A>
+<BR>string</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:label HREF=#d:label>label</A>
+</TD><TD>ENGC</TD><TD><A HREF=#k:lblString>lblString</A>
+</TD><TD ALIGN="CENTER">"\N" (nodes)<BR>"" (otherwise)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelURL HREF=#d:labelURL>labelURL</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:labelangle HREF=#d:labelangle>labelangle</A>
+</TD><TD>E</TD><TD>double</TD><TD ALIGN="CENTER">-25.0</TD><TD>-180.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labeldistance HREF=#d:labeldistance>labeldistance</A>
+</TD><TD>E</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD>0.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelfloat HREF=#d:labelfloat>labelfloat</A>
+</TD><TD>E</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelfontcolor HREF=#d:labelfontcolor>labelfontcolor</A>
+</TD><TD>E</TD><TD><A HREF=#k:color>color</A>
+</TD><TD ALIGN="CENTER">black</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelfontname HREF=#d:labelfontname>labelfontname</A>
+</TD><TD>E</TD><TD>string</TD><TD ALIGN="CENTER">"Times-Roman"</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelfontsize HREF=#d:labelfontsize>labelfontsize</A>
+</TD><TD>E</TD><TD>double</TD><TD ALIGN="CENTER">14.0</TD><TD>1.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelhref HREF=#d:labelhref>labelhref</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:labeljust HREF=#d:labeljust>labeljust</A>
+</TD><TD>GC</TD><TD>string</TD><TD ALIGN="CENTER">"c"</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labelloc HREF=#d:labelloc>labelloc</A>
+</TD><TD>GC</TD><TD>string</TD><TD ALIGN="CENTER">"t"(clusters)<BR>"b"(root graphs)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=aa:labelloc HREF=#dd:labelloc>labelloc</A>
+</TD><TD>N</TD><TD>string</TD><TD ALIGN="CENTER">"c"(clusters)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:labeltarget HREF=#d:labeltarget>labeltarget</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:labeltooltip HREF=#d:labeltooltip>labeltooltip</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, cmap only</TD> </TR>
+<TR><TD><A NAME=a:landscape HREF=#d:landscape>landscape</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:layer HREF=#d:layer>layer</A>
+</TD><TD>EN</TD><TD><A HREF=#k:layerRange>layerRange</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:layers HREF=#d:layers>layers</A>
+</TD><TD>G</TD><TD><A HREF=#k:layerList>layerList</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:layersep HREF=#d:layersep>layersep</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">" :\t"</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:layout HREF=#d:layout>layout</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:len HREF=#d:len>len</A>
+</TD><TD>E</TD><TD>double</TD><TD ALIGN="CENTER">1.0(neato)<BR>0.3(fdp)</TD><TD></TD><TD>fdp, neato only</TD> </TR>
+<TR><TD><A NAME=a:levels HREF=#d:levels>levels</A>
+</TD><TD>G</TD><TD>int</TD><TD ALIGN="CENTER">MAXINT</TD><TD>0.0</TD><TD>sfdp only</TD> </TR>
+<TR><TD><A NAME=a:levelsgap HREF=#d:levelsgap>levelsgap</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">0.0</TD><TD></TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:lhead HREF=#d:lhead>lhead</A>
+</TD><TD>E</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:lp HREF=#d:lp>lp</A>
+</TD><TD>EGC</TD><TD><A HREF=#k:point>point</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>write only</TD> </TR>
+<TR><TD><A NAME=a:ltail HREF=#d:ltail>ltail</A>
+</TD><TD>E</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:margin HREF=#d:margin>margin</A>
+</TD><TD>NG</TD><TD>double<BR><A HREF=#k:pointf>pointf</A>
+</TD><TD ALIGN="CENTER">&#60;device-dependent&#62;</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:maxiter HREF=#d:maxiter>maxiter</A>
+</TD><TD>G</TD><TD>int</TD><TD ALIGN="CENTER">100 * # nodes(mode == KK)<BR>200(mode == major)<BR>600(fdp)</TD><TD></TD><TD>fdp, neato only</TD> </TR>
+<TR><TD><A NAME=a:mclimit HREF=#d:mclimit>mclimit</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:mindist HREF=#d:mindist>mindist</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD>0.0</TD><TD>circo only</TD> </TR>
+<TR><TD><A NAME=a:minlen HREF=#d:minlen>minlen</A>
+</TD><TD>E</TD><TD>int</TD><TD ALIGN="CENTER">1</TD><TD>0</TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:mode HREF=#d:mode>mode</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">"major"</TD><TD></TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:model HREF=#d:model>model</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">"shortpath"</TD><TD></TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:mosek HREF=#d:mosek>mosek</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>neato only</TD> </TR>
+<TR><TD><A NAME=a:nodesep HREF=#d:nodesep>nodesep</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">0.25</TD><TD>0.02</TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:nojustify HREF=#d:nojustify>nojustify</A>
+</TD><TD>GCNE</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:normalize HREF=#d:normalize>normalize</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:nslimit HREF=#d:nslimit>nslimit</A>
+<BR><A NAME=a:nslimit1 HREF=#d:nslimit1>nslimit1</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:ordering HREF=#d:ordering>ordering</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:orientation HREF=#d:orientation>orientation</A>
+</TD><TD>N</TD><TD>double</TD><TD ALIGN="CENTER">0.0</TD><TD>360.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=aa:orientation HREF=#dd:orientation>orientation</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:outputorder HREF=#d:outputorder>outputorder</A>
+</TD><TD>G</TD><TD><A HREF=#k:outputMode>outputMode</A>
+</TD><TD ALIGN="CENTER">breadthfirst</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:overlap HREF=#d:overlap>overlap</A>
+</TD><TD>G</TD><TD>string<BR><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">true</TD><TD></TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:overlap_scaling HREF=#d:overlap_scaling>overlap_scaling</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">-4</TD><TD>-1.0e10</TD><TD>prism only</TD> </TR>
+<TR><TD><A NAME=a:pack HREF=#d:pack>pack</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+<BR>int</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:packmode HREF=#d:packmode>packmode</A>
+</TD><TD>G</TD><TD><A HREF=#k:packMode>packMode</A>
+</TD><TD ALIGN="CENTER">node</TD><TD></TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:pad HREF=#d:pad>pad</A>
+</TD><TD>G</TD><TD>double<BR><A HREF=#k:pointf>pointf</A>
+</TD><TD ALIGN="CENTER">0.0555 (4 points)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:page HREF=#d:page>page</A>
+</TD><TD>G</TD><TD><A HREF=#k:pointf>pointf</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:pagedir HREF=#d:pagedir>pagedir</A>
+</TD><TD>G</TD><TD><A HREF=#k:pagedir>pagedir</A>
+</TD><TD ALIGN="CENTER">BL</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:pencolor HREF=#d:pencolor>pencolor</A>
+</TD><TD>C</TD><TD><A HREF=#k:color>color</A>
+</TD><TD ALIGN="CENTER">black</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:penwidth HREF=#d:penwidth>penwidth</A>
+</TD><TD>CNE</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD>0.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:peripheries HREF=#d:peripheries>peripheries</A>
+</TD><TD>NC</TD><TD>int</TD><TD ALIGN="CENTER">shape default(nodes)<BR>1(clusters)</TD><TD>0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:pin HREF=#d:pin>pin</A>
+</TD><TD>N</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>fdp, neato only</TD> </TR>
+<TR><TD><A NAME=a:pos HREF=#d:pos>pos</A>
+</TD><TD>EN</TD><TD><A HREF=#k:point>point</A>
+<BR><A HREF=#k:splineType>splineType</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:quadtree HREF=#d:quadtree>quadtree</A>
+</TD><TD>G</TD><TD><A HREF=#k:quadType>quadType</A>
+<BR><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">"normal"</TD><TD></TD><TD>sfdp only</TD> </TR>
+<TR><TD><A NAME=a:quantum HREF=#d:quantum>quantum</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">0.0</TD><TD>0.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:rank HREF=#d:rank>rank</A>
+</TD><TD>S</TD><TD><A HREF=#k:rankType>rankType</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:rankdir HREF=#d:rankdir>rankdir</A>
+</TD><TD>G</TD><TD><A HREF=#k:rankdir>rankdir</A>
+</TD><TD ALIGN="CENTER">TB</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:ranksep HREF=#d:ranksep>ranksep</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">0.5(dot)<BR>1.0(twopi)</TD><TD>0.02</TD><TD>twopi, dot only</TD> </TR>
+<TR><TD><A NAME=a:ratio HREF=#d:ratio>ratio</A>
+</TD><TD>G</TD><TD>double<BR>string</TD><TD ALIGN="CENTER"></TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:rects HREF=#d:rects>rects</A>
+</TD><TD>N</TD><TD><A HREF=#k:rect>rect</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>write only</TD> </TR>
+<TR><TD><A NAME=a:regular HREF=#d:regular>regular</A>
+</TD><TD>N</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:remincross HREF=#d:remincross>remincross</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">false</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:repulsiveforce HREF=#d:repulsiveforce>repulsiveforce</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD>0.0</TD><TD>sfdp only</TD> </TR>
+<TR><TD><A NAME=a:resolution HREF=#d:resolution>resolution</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">96.0<BR>0.0</TD><TD></TD><TD>svg, bitmap output only</TD> </TR>
+<TR><TD><A NAME=a:root HREF=#d:root>root</A>
+</TD><TD>GN</TD><TD>string<BR><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">""(graphs)<BR>false(nodes)</TD><TD></TD><TD>circo, twopi only</TD> </TR>
+<TR><TD><A NAME=a:rotate HREF=#d:rotate>rotate</A>
+</TD><TD>G</TD><TD>int</TD><TD ALIGN="CENTER">0</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:samehead HREF=#d:samehead>samehead</A>
+</TD><TD>E</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:sametail HREF=#d:sametail>sametail</A>
+</TD><TD>E</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:samplepoints HREF=#d:samplepoints>samplepoints</A>
+</TD><TD>N</TD><TD>int</TD><TD ALIGN="CENTER">8(output)<BR>20(overlap and image maps)</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:searchsize HREF=#d:searchsize>searchsize</A>
+</TD><TD>G</TD><TD>int</TD><TD ALIGN="CENTER">30</TD><TD></TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:sep HREF=#d:sep>sep</A>
+</TD><TD>G</TD><TD>double<BR><A HREF=#k:pointf>pointf</A>
+</TD><TD ALIGN="CENTER">+4</TD><TD></TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:shape HREF=#d:shape>shape</A>
+</TD><TD>N</TD><TD><A HREF=#k:shape>shape</A>
+</TD><TD ALIGN="CENTER">ellipse</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:shapefile HREF=#d:shapefile>shapefile</A>
+</TD><TD>N</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:showboxes HREF=#d:showboxes>showboxes</A>
+</TD><TD>ENG</TD><TD>int</TD><TD ALIGN="CENTER">0</TD><TD>0</TD><TD>dot only</TD> </TR>
+<TR><TD><A NAME=a:sides HREF=#d:sides>sides</A>
+</TD><TD>N</TD><TD>int</TD><TD ALIGN="CENTER">4</TD><TD>0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:size HREF=#d:size>size</A>
+</TD><TD>G</TD><TD><A HREF=#k:pointf>pointf</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:skew HREF=#d:skew>skew</A>
+</TD><TD>N</TD><TD>double</TD><TD ALIGN="CENTER">0.0</TD><TD>-100.0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:smoothing HREF=#d:smoothing>smoothing</A>
+</TD><TD>G</TD><TD><A HREF=#k:smoothType>smoothType</A>
+</TD><TD ALIGN="CENTER">"none"</TD><TD></TD><TD>sfdp only</TD> </TR>
+<TR><TD><A NAME=a:sortv HREF=#d:sortv>sortv</A>
+</TD><TD>GCN</TD><TD>int</TD><TD ALIGN="CENTER">0</TD><TD>0</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:splines HREF=#d:splines>splines</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+<BR>string</TD><TD ALIGN="CENTER"></TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:start HREF=#d:start>start</A>
+</TD><TD>G</TD><TD><A HREF=#k:startType>startType</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>fdp, neato only</TD> </TR>
+<TR><TD><A NAME=a:style HREF=#d:style>style</A>
+</TD><TD>ENC</TD><TD><A HREF=#k:style>style</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:stylesheet HREF=#d:stylesheet>stylesheet</A>
+</TD><TD>G</TD><TD>string</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg only</TD> </TR>
+<TR><TD><A NAME=a:tailURL HREF=#d:tailURL>tailURL</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:tailclip HREF=#d:tailclip>tailclip</A>
+</TD><TD>E</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER">true</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:tailhref HREF=#d:tailhref>tailhref</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:taillabel HREF=#d:taillabel>taillabel</A>
+</TD><TD>E</TD><TD><A HREF=#k:lblString>lblString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:tailport HREF=#d:tailport>tailport</A>
+</TD><TD>E</TD><TD><A HREF=#k:portPos>portPos</A>
+</TD><TD ALIGN="CENTER">center</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:tailtarget HREF=#d:tailtarget>tailtarget</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:tailtooltip HREF=#d:tailtooltip>tailtooltip</A>
+</TD><TD>E</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, cmap only</TD> </TR>
+<TR><TD><A NAME=a:target HREF=#d:target>target</A>
+</TD><TD>ENGC</TD><TD><A HREF=#k:escString>escString</A>
+<BR>string</TD><TD ALIGN="CENTER">&#60;none&#62;</TD><TD></TD><TD>svg, map only</TD> </TR>
+<TR><TD><A NAME=a:tooltip HREF=#d:tooltip>tooltip</A>
+</TD><TD>NEC</TD><TD><A HREF=#k:escString>escString</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD>svg, cmap only</TD> </TR>
+<TR><TD><A NAME=a:truecolor HREF=#d:truecolor>truecolor</A>
+</TD><TD>G</TD><TD><A HREF=#k:bool>bool</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>bitmap output only</TD> </TR>
+<TR><TD><A NAME=a:vertices HREF=#d:vertices>vertices</A>
+</TD><TD>N</TD><TD><A HREF=#k:pointfList>pointfList</A>
+</TD><TD ALIGN="CENTER"></TD><TD></TD><TD>write only</TD> </TR>
+<TR><TD><A NAME=a:viewport HREF=#d:viewport>viewport</A>
+</TD><TD>G</TD><TD><A HREF=#k:viewPort>viewPort</A>
+</TD><TD ALIGN="CENTER">""</TD><TD></TD><TD></TD> </TR>
+<TR><TD><A NAME=a:voro_margin HREF=#d:voro_margin>voro_margin</A>
+</TD><TD>G</TD><TD>double</TD><TD ALIGN="CENTER">0.05</TD><TD>0.0</TD><TD>not dot</TD> </TR>
+<TR><TD><A NAME=a:weight HREF=#d:weight>weight</A>
+</TD><TD>E</TD><TD>double</TD><TD ALIGN="CENTER">1.0</TD><TD>0(dot)<BR>1(neato,fdp,sfdp)</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:width HREF=#d:width>width</A>
+</TD><TD>N</TD><TD>double</TD><TD ALIGN="CENTER">0.75</TD><TD>0.01</TD><TD></TD> </TR>
+<TR><TD><A NAME=a:z HREF=#d:z>z</A>
+</TD><TD>N</TD><TD>double</TD><TD ALIGN="CENTER">0.0</TD><TD>-MAXFLOAT<BR>-1000</TD><TD></TD> </TR>
+</TABLE>
+<HR>
+<H1>Attribute Descriptions</H1>
+<DL>
+<DT><A NAME=d:Damping HREF=#a:Damping><STRONG>Damping</STRONG></A>
+<DD>  Factor damping force motions. On each iteration, a nodes movement
+is limited to this factor of its potential motion. By being less than
+1.0, the system tends to ``cool'', thereby preventing cycling.
+<DT><A NAME=d:K HREF=#a:K><STRONG>K</STRONG></A>
+<DD>  Spring constant used in virtual physical model. It roughly corresponds
+to an ideal edge length (in inches), in that increasing K tends to
+increase the distance between nodes.
+Note that the edge attribute <A HREF=#d:len>len</A> can be used to
+override this value for adjacent nodes.
+<DT><A NAME=d:URL HREF=#a:URL><STRONG>URL</STRONG></A>
+<DD>  Hyperlinks incorporated into device-dependent output.
+At present, used in ps2, cmap, i*map and svg formats.
+For all these formats, URLs can be attached to nodes, edges and
+clusters. URL attributes can also be attached to the root graph in ps2,
+cmap and i*map formats. This serves as the base URL for relative URLs in the
+former, and as the default image map file in the latter.
+<P>
+For svg, cmapx and imap output, the active area for a node is its
+visible image.
+For example, an unfilled
+node with no drawn boundary will only be active on its label.
+For other output, the active area is its bounding box.
+The active area for a cluster is its bounding box.
+For edges, the active areas are small circles where the edge contacts its head
+and tail nodes. In addition, for svg, cmapx and imap, the active area
+includes a thin polygon approximating the edge. The circles may
+overlap the related node, and the edge URL dominates.
+If the edge has a label, this will also be active.
+Finally, if the edge has a head or tail label, this will also be active.
+<P>
+Note that, for edges, the attributes <A HREF=#d:headURL>headURL</A>,
+<A HREF=#d:tailURL>tailURL</A>, <A HREF=#d:labelURL>labelURL</A> and
+<A HREF=#d:edgeURL>edgeURL</A> allow control of various parts of an
+edge.
+Also note that, if active areas of two edges overlap, it is unspecified
+which area dominates.
+<DT><A NAME=d:arrowhead HREF=#a:arrowhead><STRONG>arrowhead</STRONG></A>
+<DD>  Style of arrowhead on the head node of an edge.
+See also the <A HREF=#d:dir>dir</A> attribute,
+and a <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:arrowsize HREF=#a:arrowsize><STRONG>arrowsize</STRONG></A>
+<DD>  Multiplicative scale factor for arrowheads.
+<DT><A NAME=d:arrowtail HREF=#a:arrowtail><STRONG>arrowtail</STRONG></A>
+<DD>  Style of arrowhead on the tail node of an edge.
+See also the <A HREF=#d:dir>dir</A> attribute,
+and a <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:aspect HREF=#a:aspect><STRONG>aspect</STRONG></A>
+<DD>  Target aspect ratio (width of the layout divided by the height)
+of the graph drawing. If unset, dot minimizes the total edge length.
+For certain graphs, like those with large fan-in or fan-out, this can
+lead to very wide layouts. Setting <TT>aspect</TT> will cause dot to try
+to adjust the layout to get an aspect ratio close to that specified
+by <TT>aspect</TT>.
+<P>
+By default, dot will do 5 passes attempting to achieve the desired
+aspect ratio. For certain graphs, more passes will be needed to get
+close enough. The <TT>aspect</TT> attribute can also be used to
+specify the maximum number of passes to try.
+<P>
+At present, there is no mechanism for widening a very tall layout.
+Also, the algorithm doesn't handle clusters, nor disconnected graphs.
+For the latter case, one can split the pipeline<BR>
+<TT>ccomps -x | dot | gvpack | neato -n2</TT>
+to get a similar effect.
+<DT><A NAME=d:bb HREF=#a:bb><STRONG>bb</STRONG></A>
+<DD>  Bounding box of drawing in points.
+<DT><A NAME=d:bgcolor HREF=#a:bgcolor><STRONG>bgcolor</STRONG></A>
+<DD>  When attached to the root graph, this color is used as the background for
+entire canvas. When a cluster attribute, it is used as the initial
+background for the cluster. If a cluster has a filled
+<A HREF=#d:style>style</A>, the
+cluster's <A HREF=#d:fillcolor>fillcolor</A> will overlay the
+background color.
+<P>
+If no background color is specified for the root graph, no graphics
+operation are performed on the background. This works fine for
+PostScript but for bitmap output, all bits are initialized to something.
+This means that when the bitmap output is included in some other
+document, all of the bits within the bitmap's bounding box will be
+set, overwriting whatever color or graphics where already on the page.
+If this effect is not desired, and you only want to set bits explicitly
+assigned in drawing the graph, set <B>bgcolor</B>="transparent".
+<DT><A NAME=d:center HREF=#a:center><STRONG>center</STRONG></A>
+<DD>  If true, the drawing is centered in the output canvas.
+<DT><A NAME=d:charset HREF=#a:charset><STRONG>charset</STRONG></A>
+<DD>  Specifies the character encoding used when interpreting string input
+as a text label. The default value is <TT>"UTF-8"</TT>.
+The other legal value is <TT>"iso-8859-1"</TT> or,
+equivalently,
+<TT>"Latin1"</TT>. The <B>charset</B> attribute is case-insensitive.
+Note that if the character encoding used in the input does not
+match the <B>charset</B> value, the resulting output may be very strange.
+<DT><A NAME=d:clusterrank HREF=#a:clusterrank><STRONG>clusterrank</STRONG></A>
+<DD>  Mode used for handling clusters. If <B>clusterrank</B> is "local", a
+subgraph whose name begins with "cluster" is given special treatment.
+The subgraph is laid out separately, and then integrated as a unit into
+its parent graph, with a bounding rectangle drawn about it.
+If the cluster has a <A HREF=#d:label>label</A> parameter, this label
+is displayed within the rectangle.
+Note also that there can be clusters within clusters.
+At present, the modes "global" and "none"
+appear to be identical, both turning off the special cluster processing.
+<DT><A NAME=d:color HREF=#a:color><STRONG>color</STRONG></A>
+<DD>  Basic drawing color for graphics, not text. For the latter, use the
+<A HREF=#d.fontcolor>fontcolor</A> attribute.
+<P>
+For edges, the value
+can either be a single color or a <A HREF=#k:colorList>colorList</A>.
+In the latter case, the edge is drawn using parallel splines or lines,
+one for each color in the list, in the order given.
+The head arrow, if any, is drawn using the first color in the list,
+and the tail arrow, if any, the second color. This supports the common
+case of drawing opposing edges, but using parallel splines instead of
+separately routed multiedges. For example, the graph
+<PRE>
+digraph G {
+a -> b [dir=both color="red:blue"]
+}
+</PRE>
+yields<BR>
+<IMG SRC="colorlist.gif">
+<DT><A NAME=d:colorscheme HREF=#a:colorscheme><STRONG>colorscheme</STRONG></A>
+<DD>  This attribute specifies a color scheme namespace. If defined, it specifies
+the context for interpreting color names. In particular, if a
+<A HREF=#k:color>color</A> value has form <TT>"xxx"</TT> or <TT>"//xxx"</TT>,
+then the
+color <TT>xxx</TT> will be evaluated according to the current color scheme.
+If no color scheme is set, the standard X11 naming is used.
+For example, if <TT>colorscheme=bugn9</TT>, then <TT>color=7</TT>
+is interpreted as <TT>"/bugn9/7"</TT>.
+<DT><A NAME=d:comment HREF=#a:comment><STRONG>comment</STRONG></A>
+<DD>  Comments are inserted into output. Device-dependent
+<DT><A NAME=d:compound HREF=#a:compound><STRONG>compound</STRONG></A>
+<DD>  If true, allow edges between clusters. (See <A HREF=#d:lhead>lhead</A>
+and <A HREF=#d:ltail>ltail</A> below.)
+<DT><A NAME=d:concentrate HREF=#a:concentrate><STRONG>concentrate</STRONG></A>
+<DD>  If true, use edge concentrators.
+This merges multiedges into a single edge and causes partially parallel
+edges to share part of their paths. The latter feature is not yet available
+outside of dot.
+<DT><A NAME=d:constraint HREF=#a:constraint><STRONG>constraint</STRONG></A>
+<DD>  If false, the edge is not used in ranking the nodes. For example,
+in the graph
+<PRE>
+digraph G {
+a -> c;
+a -> b;
+b -> c [constraint=false];
+}
+</PRE>
+the edge <CODE>b -> c</CODE> does not add a constraint during rank
+assignment, so the only constraints are that a be above b and c,
+yielding the graph:<BR>
+<IMG SRC="constraint.gif">
+<DT><A NAME=d:decorate HREF=#a:decorate><STRONG>decorate</STRONG></A>
+<DD>  If true, attach edge label to edge by a 2-segment
+polyline, underlining the label, then going to the closest point of spline.
+<DT><A NAME=d:defaultdist HREF=#a:defaultdist><STRONG>defaultdist</STRONG></A>
+<DD>  This specifies the distance between nodes in separate connected
+components. If set too small, connected components may overlap.
+Only applicable if <A HREF=#d:pack>pack</A>=false.
+<DT><A NAME=d:dim HREF=#a:dim><STRONG>dim</STRONG></A>
+<DD>  Set the number of dimensions used for the layout. The maximum value
+allowed is 10.
+<DT><A NAME=d:dimen HREF=#a:dimen><STRONG>dimen</STRONG></A>
+<DD>  Set the number of dimensions used for rendering.
+The maximum value allowed is 10.
+If both <TT>dimen</TT> and <TT>dim</TT> are set, the latter specifies
+the dimension used for layout, and the former for rendering.
+If only <TT>dimen</TT> is set, this is used for both layout and rendering
+dimensions.
+<DT><A NAME=d:dir HREF=#a:dir><STRONG>dir</STRONG></A>
+<DD>  Set edge type for drawing arrowheads. This indicates which ends of the
+edge should be decorated with an arrowhead. The actual style of the
+arrowhead can be specified using the <A HREF=#d:arrowhead>arrowhead</A>
+and <A HREF=#d:arrowtail>arrowtail</A> attributes.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:diredgeconstraints HREF=#a:diredgeconstraints><STRONG>diredgeconstraints</STRONG></A>
+<DD>  Only valid when <A HREF=#d:mode>mode</A>="ipsep".
+If true, constraints are generated for each edge in the largest (heuristic)
+directed acyclic subgraph such that the edge must point downwards.
+If "hier", generates level constraints similar to those used with
+<A HREF=#d:mode>mode</A>="hier". The main difference is that, in the latter
+case, only these constraints are involved, so a faster solver can be used.
+<DT><A NAME=d:distortion HREF=#a:distortion><STRONG>distortion</STRONG></A>
+<DD>  Distortion factor for <A HREF=#d:shape><B>shape</B></A>=polygon.
+Positive values cause top part to
+be larger than bottom; negative values do the opposite.
+<DT><A NAME=d:dpi HREF=#a:dpi><STRONG>dpi</STRONG></A>
+<DD>  This specifies the expected number of pixels per inch on a display device.
+For bitmap output, this guarantees that text rendering will be
+done more accurately, both in size and in placement. For SVG output,
+it is used to guarantee that the dimensions in the output correspond to
+the correct number of points or inches.
+<DT><A NAME=d:edgeURL HREF=#a:edgeURL><STRONG>edgeURL</STRONG></A>
+<DD>  If <B>edgeURL</B> is defined, this is the link used for the non-label
+parts of an edge. This value overrides any <A HREF=#d:URL>URL</A>
+defined for the edge.
+Also, this value is used near the head or tail node unless overridden
+by a <A HREF=#d:headURL>headURL</A> or <A HREF=#d:tailURL>tailURL</A> value,
+respectively.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:edgehref HREF=#a:edgehref><STRONG>edgehref</STRONG></A>
+<DD>  Synonym for <A HREF=#d:edgeURL>edgeURL</A>.
+<DT><A NAME=d:edgetarget HREF=#a:edgetarget><STRONG>edgetarget</STRONG></A>
+<DD>  If the edge has a <A HREF=#d:URL>URL</A> or <A HREF=#d:edgeURL>edgeURL</A>
+attribute, this attribute determines which window of the
+browser is used
+for the URL attached to the non-label part of the edge.
+Setting it to "_graphviz" will open a new window if it
+doesn't already exist, or reuse it if it does.
+If undefined, the value of the <A HREF=#d:target>target</A> is used.
+<DT><A NAME=d:edgetooltip HREF=#a:edgetooltip><STRONG>edgetooltip</STRONG></A>
+<DD>  Tooltip annotation attached to the non-label part of an edge.
+This is used only if the edge has a <A HREF=#d:URL>URL</A>
+or <A HREF=#d:edgeURL>edgeURL</A> attribute.
+<DT><A NAME=d:epsilon HREF=#a:epsilon><STRONG>epsilon</STRONG></A>
+<DD>  Terminating condition. If the length squared of all energy gradients are
+< <B>epsilon</B>, the algorithm stops.
+<DT><A NAME=d:esep HREF=#a:esep><STRONG>esep</STRONG></A>
+<DD>  Margin used around polygons for purposes of spline edge routing.
+The interpretation is the same as given for <A HREF=#d:sep>sep</A>.
+This should normally be strictly less than <A HREF=#d:sep>sep</A>.
+<DT><A NAME=d:fillcolor HREF=#a:fillcolor><STRONG>fillcolor</STRONG></A>
+<DD>  Color used to fill the background of a node or cluster
+assuming <A HREF=#d:style>style</A>=filled.
+If <B>fillcolor</B> is not defined, <A HREF=#d:color>color</A> is
+used. (For clusters, if <B>color</B> is not defined,
+<A HREF=#d:bgcolor>bgcolor</A> is used.) If this is not defined,
+the default is used, except for
+<A HREF=#d:shape><B>shape</B></A>=point or when the output
+format is MIF,
+which use black by default.
+<P>
+Note that a cluster inherits the root graph's attributes if defined.
+Thus, if the root graph has defined a <B>fillcolor</B>, this will override a
+<B>color</B> or <B>bgcolor</B> attribute set for the cluster.
+<DT><A NAME=d:fixedsize HREF=#a:fixedsize><STRONG>fixedsize</STRONG></A>
+<DD>  If true, the node size is specified by the values of the
+<A HREF=#d:width><B>width</B></A>
+and <A HREF=#d:height><B>height</B></A> attributes only
+and is not expanded to contain the text label.
+<DT><A NAME=d:fontcolor HREF=#a:fontcolor><STRONG>fontcolor</STRONG></A>
+<DD>  Color used for text.
+<DT><A NAME=d:fontname HREF=#a:fontname><STRONG>fontname</STRONG></A>
+<DD>  Font used for text. This very much depends on the output format and, for
+non-bitmap output such as PostScript or SVG, the availability of the font
+when the graph is displayed or printed. As such, it is best to rely on
+font faces that are generally available, such as Times-Roman, Helvetica or
+Courier.
+<P>
+If Graphviz was built using the
+<A HREF=http://pdx.freedesktop.org/~fontconfig/fontconfig-user.html>fontconfig library</A>, the latter library
+will be used to search for the font. However, if the <TT>fontname</TT> string
+contains a slash character "/", it is treated as a pathname for the font
+file, though font lookup will append the usual font suffixes.
+<P>
+If Graphviz does not use fontconfig, <TT>fontname</TT> will be
+considered the name of a Type 1 or True Type font file.
+If you specify <TT>fontname=schlbk</TT>, the tool will look for a
+file named  <TT>schlbk.ttf</TT> or <TT>schlbk.pfa</TT> or <TT>schlbk.pfb</TT>
+in one of the directories specified by
+the <A HREF=#d:fontpath>fontpath</A> attribute.
+The lookup does support various aliases for the common fonts.
+<DT><A NAME=d:fontnames HREF=#a:fontnames><STRONG>fontnames</STRONG></A>
+<DD>  Allows user control of how basic fontnames are represented in SVG output.
+If <TT>fontnames</TT> is undefined or <TT>"svg"</TT>,
+the output will try to use known SVG fontnames. For example, the
+default font  <TT>"Times-Roman"</TT> will be mapped to the
+basic SVG font <TT>"serif"</TT>. This can be overridden by setting
+<TT>fontnames</TT> to  <TT>"ps"</TT> or  <TT>"gd"</TT>.
+In the former case, known PostScript font names such as
+<TT>"Times-Roman"</TT> will be used in the output.
+In the latter case, the fontconfig font conventions
+are used. Thus, <TT>"Times-Roman"</TT> would be treated as
+<TT>"Nimbus Roman No9 L"</TT>. These last two options are useful
+with SVG viewers that support these richer fontname spaces.
+<DT><A NAME=d:fontpath HREF=#a:fontpath><STRONG>fontpath</STRONG></A>
+<DD>  Directory list used by libgd to search for bitmap fonts if Graphviz
+was not built with the fontconfig library.
+If <B>fontpath</B> is not set, the environment
+variable <TT>DOTFONTPATH</TT> is checked.
+If that is not set, <TT>GDFONTPATH</TT> is checked.
+If not set, libgd uses its compiled-in font path.
+Note that fontpath is an attribute of the root graph.
+<DT><A NAME=d:fontsize HREF=#a:fontsize><STRONG>fontsize</STRONG></A>
+<DD>  Font size, <A HREF=#points>in points</A>, used for text.
+<DT><A NAME=d:group HREF=#a:group><STRONG>group</STRONG></A>
+<DD>  If the end points of an edge belong to the same group, i.e., have the
+same group attribute, parameters are set to avoid crossings and keep
+the edges straight.
+<DT><A NAME=d:headURL HREF=#a:headURL><STRONG>headURL</STRONG></A>
+<DD>  If <B>headURL</B> is defined, it is
+output as part of the head label of the edge.
+Also, this value is used near the head node, overriding any
+<A HREF=#d:URL>URL</A> value.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:headclip HREF=#a:headclip><STRONG>headclip</STRONG></A>
+<DD>  If true, the head of an edge is clipped to the boundary of the head node;
+otherwise, the end of the edge goes to the center of the node, or the
+center of a port, if applicable.
+<DT><A NAME=d:headhref HREF=#a:headhref><STRONG>headhref</STRONG></A>
+<DD>  Synonym for <A HREF=#d:headURL>headURL</A>.
+<DT><A NAME=d:headlabel HREF=#a:headlabel><STRONG>headlabel</STRONG></A>
+<DD>  Text label to be placed near head of edge.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:headport HREF=#a:headport><STRONG>headport</STRONG></A>
+<DD>  Indicates where on the head node to attach the head of the edge.
+In the default case, the edge is aimed towards the center of the node,
+and then clipped at the node boundary.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:headtarget HREF=#a:headtarget><STRONG>headtarget</STRONG></A>
+<DD>  If the edge has a <A HREF=#d:headURL>headURL</A>,
+this attribute determines 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 undefined, the value of the <A HREF=#d:target>target</A> is used.
+<DT><A NAME=d:headtooltip HREF=#a:headtooltip><STRONG>headtooltip</STRONG></A>
+<DD>  Tooltip annotation attached to the head of an edge. This is used only
+if the edge has a <A HREF=#d:headURL>headURL</A> attribute.
+<DT><A NAME=d:height HREF=#a:height><STRONG>height</STRONG></A>
+<DD>  Height of node, in inches. This is taken as the initial, minimum height
+of the node. If <A HREF=#d:fixedsize><B>fixedsize</B></A> is true, this
+will be the final height of the node. Otherwise, if the node label
+requires more height to fit, the node's height will be increased to
+contain the label. Note also that, if the output format is dot, the
+value given to <B>height</B> will be the final value.
+<DT><A NAME=d:href HREF=#a:href><STRONG>href</STRONG></A>
+<DD>  Synonym for <A HREF=#d:URL>URL</A>.
+<DT><A NAME=d:id HREF=#a:id><STRONG>id</STRONG></A>
+<DD>  Allows the graph author to provide an id for graph objects which is to be included in the output.
+Normal "N", "E", "G" substitutions are applied.
+If provided, it is the reponsiblity of the provider to keep
+its values sufficiently unique for its intended downstream use.
+Note, in particular, that "E" does not provide a unique id for multi-edges.
+If no id attribute is provided, then a unique internal id is used, however this value is unpredictable by the graph writer.
+An externally provided id is not used internally.
+<DT><A NAME=d:image HREF=#a:image><STRONG>image</STRONG></A>
+<DD>  Gives the name of a file containing an image to be displayed inside
+a node. The image file must be in one of the recognized
+<A HREF=output.html#d:image_fmts>formats</A>,
+typically JPEG, PNG, GIF or Postscript, and be able to be converted
+into the desired output format.
+<P>
+Unlike with the <A HREF=#d:shapefile>shapefile</A> attribute,
+the image is treated as node
+content rather than the entire node. In particular, an image can
+be contained in a node of any shape, not just a rectangle.
+<DT><A NAME=d:imagescale HREF=#a:imagescale><STRONG>imagescale</STRONG></A>
+<DD>  Attribute controlling how an image fills its
+containing node. In general, the image is given its natural size,
+(cf. <A HREF=#d:dpi>dpi</A>),
+and the node size is made large enough to contain its image, its
+label, its margin, and its peripheries.
+Its width and height will also be at least as large as its
+minimum <A HREF=#d:width>width</A> and <A HREF=#d:height>height</A>.
+If, however, <TT>fixedsize=true</TT>,
+the width and height attributes specify the exact size of the node.
+<P>
+During rendering, in the default case (<TT>imagescale=false</TT>),
+the image retains its natural size.
+If <TT>imagescale=true</TT>,
+the image is uniformly scaled (i.e., its aspect ratio is
+preserved) to fit inside the node.
+At least one dimension of the image will be as large as possible
+given the size of the node.
+When <TT>imagescale=width</TT>,
+the width of the image is scaled to fill the node width.
+The corresponding property holds when <TT>imagescale=height</TT>.
+When <TT>imagescale=both</TT>,
+both the height and the width are scaled separately to fill the node.
+<P>
+In all cases, if a dimension of the image is larger than the
+corresponding dimension of the node, that dimension of the
+image is scaled down to fit the node. As with the case of
+expansion, if  <TT>imagescale=true</TT>, width and height are
+scaled uniformly.
+<DT><A NAME=d:label HREF=#a:label><STRONG>label</STRONG></A>
+<DD>  Text label attached to objects.
+If a node's <A HREF=#d:shape>shape</A> is record, then the label can
+have a <A HREF=shapes.html#record>special format</A>
+which describes the record layout.
+<DT><A NAME=d:labelURL HREF=#a:labelURL><STRONG>labelURL</STRONG></A>
+<DD>  If <B>labelURL</B> is defined, this is the link used for the label
+of an edge. This value overrides any <A HREF=#d:URL>URL</A>
+defined for the edge.
+<DT><A NAME=d:labelangle HREF=#a:labelangle><STRONG>labelangle</STRONG></A>
+<DD>  This, along with <A HREF=#d:labeldistance>labeldistance</A>, determine
+where the
+headlabel (taillabel) are placed with respect to the head (tail)
+in polar coordinates. The origin in the coordinate system is
+the point where the edge touches the node. The ray of 0 degrees
+goes from the origin back along the edge, parallel to the edge
+at the origin.
+<P>
+The angle, in degrees, specifies the rotation from the 0 degree ray,
+with positive angles moving counterclockwise and negative angles
+moving clockwise.
+<DT><A NAME=d:labeldistance HREF=#a:labeldistance><STRONG>labeldistance</STRONG></A>
+<DD>  Multiplicative scaling factor adjusting the distance that
+the headlabel(taillabel) is from the head(tail) node.
+The default distance is 10 points. See <A HREF=#d:labelangle>labelangle</A>
+for more details.
+<DT><A NAME=d:labelfloat HREF=#a:labelfloat><STRONG>labelfloat</STRONG></A>
+<DD>  If true, allows edge labels to be less constrained in position.
+In particular, it may appear on top of other edges.
+<DT><A NAME=d:labelfontcolor HREF=#a:labelfontcolor><STRONG>labelfontcolor</STRONG></A>
+<DD>  Color used for headlabel and taillabel.
+If not set, defaults to edge's fontcolor.
+<DT><A NAME=d:labelfontname HREF=#a:labelfontname><STRONG>labelfontname</STRONG></A>
+<DD>  Font used for headlabel and taillabel.
+If not set, defaults to edge's fontname.
+<DT><A NAME=d:labelfontsize HREF=#a:labelfontsize><STRONG>labelfontsize</STRONG></A>
+<DD>  Font size, <A HREF=#points>in points</A>, used for headlabel and taillabel.
+If not set, defaults to edge's fontsize.
+<DT><A NAME=d:labelhref HREF=#a:labelhref><STRONG>labelhref</STRONG></A>
+<DD>  Synonym for <A HREF=#d:labelURL>labelURL</A>.
+<DT><A NAME=d:labeljust HREF=#a:labeljust><STRONG>labeljust</STRONG></A>
+<DD>  Justification for cluster labels. If "r", the label
+is right-justified within bounding rectangle; if "l", left-justified;
+else the label is centered.
+Note that a subgraph inherits attributes from its parent. Thus, if
+the root graph sets <B>labeljust</B> to "l", the subgraph inherits
+this value.
+<DT><A NAME=d:labelloc HREF=#a:labelloc><STRONG>labelloc</STRONG></A>
+<DD>  Top/bottom placement of graph and cluster labels.
+If the attribute is "t", place label at the top;
+if the attribute is "b", place label at the bottom.
+By default, root
+graph labels go on the bottom and cluster labels go on the top.
+Note that a subgraph inherits attributes from its parent. Thus, if
+the root graph sets <B>labelloc</B> to "b", the subgraph inherits
+this value.
+<DT><A NAME=dd:labelloc HREF=#aa:labelloc><STRONG>labelloc</STRONG></A>
+<DD>  Vertical placement of node label. By default, if the height of a node
+is larger than the height of its label, the label is vertically centered.
+If <TT>labelloc</TT> is set to "t", "c", or "b", the label is aligned
+with the top, centered, or aligned with the bottom of the node, respectively.
+<DT><A NAME=d:labeltarget HREF=#a:labeltarget><STRONG>labeltarget</STRONG></A>
+<DD>  If the edge has a <A HREF=#d:URL>URL</A> or <A HREF=#d:labelURL>labelURL</A>
+attribute, this attribute determines which window of the
+browser is used
+for the URL attached to the label.
+Setting it to "_graphviz" will open a new window if it
+doesn't already exist, or reuse it if it does.
+If undefined, the value of the <A HREF=#d:target>target</A> is used.
+<DT><A NAME=d:labeltooltip HREF=#a:labeltooltip><STRONG>labeltooltip</STRONG></A>
+<DD>  Tooltip annotation attached to label of an edge.
+This is used only if the edge has a <A HREF=#d:URL>URL</A>
+or <A HREF=#d:labelURL>labelURL</A> attribute.
+<DT><A NAME=d:landscape HREF=#a:landscape><STRONG>landscape</STRONG></A>
+<DD>  If true, the graph is rendered in landscape mode. Synonymous with
+<A HREF=#d:rotate><TT>rotate=90</TT></A> or
+<A HREF=#d:orientation><TT>orientation=landscape</TT></A>.
+<DT><A NAME=d:layer HREF=#a:layer><STRONG>layer</STRONG></A>
+<DD>  Specifies layers in which the node or edge is present.
+<DT><A NAME=d:layers HREF=#a:layers><STRONG>layers</STRONG></A>
+<DD>  Specifies a linearly ordered list of layer names attached to the graph
+The graph is then output in separate layers. Only those components
+belonging to the current output layer appear. For more information,
+see the page <A HREF="http://www.graphviz.org/Documentation/html/layers/">How to use drawing layers (overlays)</A>.
+<DT><A NAME=d:layersep HREF=#a:layersep><STRONG>layersep</STRONG></A>
+<DD>  Specifies the separator characters used to split the
+<A HREF=#d:layers>layers </A>attribute into a list of layer names.
+<DT><A NAME=d:layout HREF=#a:layout><STRONG>layout</STRONG></A>
+<DD>  Specifies the name of the layout algorithm to use, such as "dot"
+or "neato". Normally, graphs should be kept independent of a type of
+layout. In some cases, however, it can be convenient to embed the type
+of layout desired within the graph. For example, a graph containing
+position information from a layout might want to record what the
+associated layout algorithm was.
+<P>
+This attribute takes precedence over
+the <A HREF=command.html#minusK>-K flag</A>
+or the actual command name used.
+<DT><A NAME=d:len HREF=#a:len><STRONG>len</STRONG></A>
+<DD>  Preferred edge length, in inches.
+<DT><A NAME=d:levels HREF=#a:levels><STRONG>levels</STRONG></A>
+<DD>  Number of levels allowed in the multilevel scheme.
+<DT><A NAME=d:levelsgap HREF=#a:levelsgap><STRONG>levelsgap</STRONG></A>
+<DD>  Specifies strictness of level constraints in neato
+when <TT><A HREF=#d:mode>mode</A>="ipsep" or "hier"</TT>.
+Larger positive values mean stricter constraints, which demand more
+separation between levels. On the other hand, negative values will relax
+the constraints by allowing some overlap between the levels.
+<DT><A NAME=d:lhead HREF=#a:lhead><STRONG>lhead</STRONG></A>
+<DD>  Logical head of an edge. When <A HREF=#d:compound><B>compound</B></A> is true,
+if <B>lhead</B> is defined and is the name of a cluster containing
+the real head,
+the edge is clipped to the boundary of the cluster.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:lp HREF=#a:lp><STRONG>lp</STRONG></A>
+<DD>  Label position, <A HREF=#points>in points</A>.
+The position indicates the center of the label.
+<DT><A NAME=d:ltail HREF=#a:ltail><STRONG>ltail</STRONG></A>
+<DD>  Logical tail of an edge. When <A HREF=#d:compound><B>compound</B></A> is true,
+if <B>ltail</B> is defined and is the name of a cluster
+containing the real tail,
+the edge is clipped to the boundary of the cluster.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:margin HREF=#a:margin><STRONG>margin</STRONG></A>
+<DD>  For graphs, this sets x and y margins of canvas, in inches. If the margin
+is a single double, both margins are set equal to the given value.
+<P>
+Note that the margin is not part of the drawing but just empty space
+left around the drawing. It basically corresponds to a translation of
+drawing, as would be necessary to center a drawing on a page. Nothing
+is actually drawn in the margin. To actually extend the background of
+a drawing, see the <A HREF=#d:pad>pad</A> attribute.
+<P>
+For nodes, this attribute specifies space left around the node's label.
+By default, the value is <TT>0.11,0.055</TT>.
+<DT><A NAME=d:maxiter HREF=#a:maxiter><STRONG>maxiter</STRONG></A>
+<DD>  Sets the number of iterations used.
+<DT><A NAME=d:mclimit HREF=#a:mclimit><STRONG>mclimit</STRONG></A>
+<DD>  Multiplicative scale factor used to alter the MinQuit (default = 8)
+and MaxIter (default = 24) parameters used during crossing
+minimization. These correspond to the
+number of tries without improvement before quitting and the
+maximum number of iterations in each pass.
+<DT><A NAME=d:mindist HREF=#a:mindist><STRONG>mindist</STRONG></A>
+<DD>  Specifies the minimum separation between all nodes.
+<DT><A NAME=d:minlen HREF=#a:minlen><STRONG>minlen</STRONG></A>
+<DD>  Minimum edge length (rank difference between head and tail).
+<DT><A NAME=d:mode HREF=#a:mode><STRONG>mode</STRONG></A>
+<DD>  Technique for optimizing the layout. If <B>mode</B> is <TT>"major"</TT>,
+neato uses stress majorization. If <B>mode</B> is <TT>"KK"</TT>,
+neato uses a version of the gradient descent method. The only advantage
+to the latter technique is that it is sometimes appreciably faster for
+small (number of nodes < 100) graphs. A significant disadvantage is that
+it may cycle.
+<P>
+There are two new, experimental modes in neato, "hier", which adds a top-down
+directionality similar to the layout used in dot, and "ipsep", which
+allows the graph to specify minimum vertical and horizontal distances
+between nodes. (See the <A HREF=#d:sep>sep</A> attribute.)
+<DT><A NAME=d:model HREF=#a:model><STRONG>model</STRONG></A>
+<DD>  This value specifies how the distance matrix is computed for the input
+graph. The distance matrix specifies the ideal distance between every
+pair of nodes. neato attemps to find a layout which best achieves
+these distances. By default, it uses the length of the shortest path,
+where the length of each edge is given by its <A HREF=#d:len>len</A>
+attribute. If <B>model</B> is <TT>"circuit"</TT>, neato uses the
+circuit resistance
+model to compute the distances. This tends to emphasize clusters. If
+<B>model</B> is <TT>"subset"</TT>, neato uses the subset model. This sets the
+edge length to be the number of nodes that are neighbors of exactly one
+of the end points, and then calculates the shortest paths. This helps
+to separate nodes with high degree.
+<DT><A NAME=d:mosek HREF=#a:mosek><STRONG>mosek</STRONG></A>
+<DD>  If Graphviz is built with MOSEK defined, mode=ipsep and mosek=true,
+the Mosek software (www.mosek.com) is use to solve the ipsep constraints.
+<DT><A NAME=d:nodesep HREF=#a:nodesep><STRONG>nodesep</STRONG></A>
+<DD>  Minimum space between two adjacent nodes in the same rank, in inches.
+<DT><A NAME=d:nojustify HREF=#a:nojustify><STRONG>nojustify</STRONG></A>
+<DD>  By default, the justification of multi-line labels is done within the
+largest context that makes sense. Thus, in the label of a polygonal
+node, a left-justified line will align with the left side of the node
+(shifted by the prescribed <A HREF=#d:margin>margin</A>).
+In record nodes, left-justified
+line will line up with the left side of the enclosing column of fields.
+If <B>nojustify</B> is <TT>"true"</TT>, multi-line labels will be justified
+in the context of itself. For example, if the attribute is set,
+the first label line is long, and the second is shorter and left-justified,
+the second will align with the left-most character in the first line,
+regardless of  how large the node might be.
+<DT><A NAME=d:normalize HREF=#a:normalize><STRONG>normalize</STRONG></A>
+<DD>  If set, normalize coordinates of final
+layout so that the first point is at the origin, and then rotate the
+layout so that the first edge is horizontal.
+<DT><A NAME=d:nslimit HREF=#a:nslimit><STRONG>nslimit</STRONG></A>
+,<DT><A NAME=d:nslimit1 HREF=#a:nslimit1><STRONG>nslimit1</STRONG></A>
+<DD>  Used to set number of iterations in
+network simplex applications. <B>nslimit</B> is used in
+computing node x coordinates, <B>nslimit1</B> for ranking nodes.
+If defined, # iterations =  <B>nslimit(1)</B> * # nodes;
+otherwise,  # iterations = MAXINT.
+<DT><A NAME=d:ordering HREF=#a:ordering><STRONG>ordering</STRONG></A>
+<DD>  If "out" for a graph G, and n is a node in G, then edges n->* appear
+left-to-right in the same order in which they are defined.
+If "in", the edges *->n appear
+left-to-right in the same order in which they are defined for all
+nodes n.
+<DT><A NAME=d:orientation HREF=#a:orientation><STRONG>orientation</STRONG></A>
+<DD>  Angle, in degrees, used to rotate polygon node shapes. For any number of polygon sides, 0 degrees rotation results in a flat base.
+<DT><A NAME=dd:orientation HREF=#aa:orientation><STRONG>orientation</STRONG></A>
+<DD>  If "[lL]*", set graph orientation to landscape
+Used only if <A HREF=#d:rotate><B>rotate</B></A> is not defined.
+<DT><A NAME=d:outputorder HREF=#a:outputorder><STRONG>outputorder</STRONG></A>
+<DD>  Specify order in which nodes and edges are drawn.
+<DT><A NAME=d:overlap HREF=#a:overlap><STRONG>overlap</STRONG></A>
+<DD>  Determines if and how node overlaps should be removed. Nodes are first
+enlarged using the <A HREF=#d:sep><B>sep</B></A> attribute.
+If "true" , overlaps are retained.
+If the value is "scale", overlaps are removed by uniformly scaling in x and y.
+If the value converts to "false", node overlaps are removed by a
+Voronoi-based technique.
+If the value is "scalexy", x and y are separately
+scaled to remove overlaps.
+<P>
+If sfdp is available, one can set overlap to "prism" to use a
+proximity graph-based algorithm for overlap removal.
+This is the preferred technique,
+though "scale" and "false" can work well with small graphs.
+This technique starts with a
+small scaling up, controlled by the
+<A HREF="#d:overlap_scaling"><TT>overlap_scaling</TT></A> attribute,
+which can remove a significant portion of the overlap.
+The prism option also accepts an optional non-negative integer suffix.
+This can be used to control the number of attempts made at overlap
+removal. By default, <TT>overlap="prism"</TT> is equivalent to
+<TT>overlap="prism1000"</TT>. Setting <TT>overlap="prism0"</TT>
+causes only the scaling phase to be run.
+<P>
+If the value is "compress", the layout will be scaled down as much as
+possible without introducing any overlaps, obviously assuming there are
+none to begin with.
+<P>
+<B>N.B.</B>The remaining allowed values of <TT>overlap</TT>
+correspond to algorithms which, at present, can produce bad aspect ratios.
+In addition, we deprecate the use of the "ortho*" and "portho*".
+<P>
+If the value is "vpsc", overlap removal is done as a
+quadratic optimization to minimize node displacement while removing
+node overlaps.
+<P>
+If the value is "orthoxy" or "orthoyx", overlaps
+are moved by optimizing two constraint problems, one for the x axis and
+one for the y. The suffix indicates which axis is processed first.
+If the value is "ortho", the technique is similar to "orthoxy" except a
+heuristic is used to reduce the bias between the two passes.
+If the value is "ortho_yx", the technique is the same as "ortho", except
+the roles of x and y are reversed.
+The values "portho", "porthoxy", "porthoxy", and "portho_yx" are similar
+to the previous four, except only pseudo-orthogonal ordering is
+enforced.
+<P>
+If the layout is done by neato with <A HREF=#d:mode>mode</A>="ipsep",
+then one can use <TT>overlap=ipsep</TT>.
+In this case, the overlap removal constraints are
+incorporated into the layout algorithm itself.
+N.B. At present, this only supports one level of clustering.
+<P>
+Except for fdp and sfdp, the layouts assume <TT>overlap="true"</TT> as the default.
+Fdp first uses a number of passes using built-in, force-directed technique
+to remove overlaps. Thus, fdp accepts <B>overlap</B> with an integer
+prefix followed by a colon, specifying the number of tries. If there is
+no prefix, no initial tries will be performed. If there is nothing following
+a colon, none of the above methods will be attempted. By default, fdp
+uses <TT>overlap="9:portho"</TT>. Note that <TT>overlap="true"</TT>,
+<TT>overlap="0:true"</TT> and <TT>overlap="0:"</TT> all turn off all overlap
+removal.
+<P>
+By default, sfdp uses <TT>overlap="prism0"</TT>.
+<P>
+Except for the Voronoi and prism methods, all of these transforms preserve the
+orthogonal ordering of the original layout. That is, if the x coordinates
+of two nodes are originally the same, they will remain the same, and if
+the x coordinate of one node is originally less than the x coordinate of
+another, this relation will still hold in the transformed layout. The
+similar properties hold for the y coordinates.
+This is not quite true for the "porth*" cases. For these, orthogonal
+ordering is only preserved among nodes related by an edge.
+<DT><A NAME=d:overlap_scaling HREF=#a:overlap_scaling><STRONG>overlap_scaling</STRONG></A>
+<DD>  When <TT>overlap=prism</TT>, the layout is scaled by this factor, thereby
+removing a fair amount of node overlap, and making node overlap removal
+faster and better able to retain the graph's shape.
+<P>
+If <TT>overlap_scaling</TT> is negative, the layout is scaled by
+<TT>-1*overlap_scaling</TT> times the average label size.
+If <TT>overlap_scaling</TT> is positive, the layout is scaled by
+<TT>overlap_scaling</TT>.
+If <TT>overlap_scaling</TT> is zero, no scaling is done.
+<DT><A NAME=d:pack HREF=#a:pack><STRONG>pack</STRONG></A>
+<DD>  This is true if the value of pack is "true" (case-insensitive) or a
+non-negative integer. If true, each connected component of the graph is
+laid out separately, and then the graphs are packed together.
+If pack has an integral value, this is used as the size,
+in <A HREF=#points>points</A>, of
+a margin around each part; otherwise, a default margin of 8 is used.
+If pack is interpreted as false, the entire graph is laid out together.
+The granularity and method of packing is influenced by the
+<A HREF=#d:packmode>packmode</A> attribute.
+<P>
+For layouts which always do packing, such a twopi, the <B>pack</B>
+attribute is just used to set the margin.
+<DT><A NAME=d:packmode HREF=#a:packmode><STRONG>packmode</STRONG></A>
+<DD>  This indicates how connected components should be packed
+(cf. <A HREF=#k:packMode>packMode</A>). Note that defining
+<B>packmode</B> will automatically turn on packing as though one had
+set <B>pack=true</B>.
+<DT><A NAME=d:pad HREF=#a:pad><STRONG>pad</STRONG></A>
+<DD>  The pad attribute specifies how much, in inches, to extend the
+drawing area around the minimal area needed to draw the graph.
+If the pad is a single double, both the x and y pad values are set
+equal to the given value. This area is part of the
+drawing and will be filled with the background color, if appropriate.
+<P>
+Normally, a small pad is used for aesthetic reasons, especially when
+a background color is used, to avoid having nodes and edges abutting
+the boundary of the drawn region.
+<DT><A NAME=d:page HREF=#a:page><STRONG>page</STRONG></A>
+<DD>  Width and height of output pages, in inches. If this is set and is
+smaller than the size of the layout, a rectangular array of pages of
+the specified page size is overlaid on the layout, with origins
+aligned in the lower-left corner, thereby partitioning the layout
+into pages. The pages are then produced one at a time, in
+<A HREF=#d:pagedir>pagedir</A> order.
+<P>
+At present, this only works for PostScript output. For other types of
+output, one should use another tool to split the output into multiple
+output files. Or use the <A HREF=#d:viewport>viewport</A> to generate
+multiple files.
+<DT><A NAME=d:pagedir HREF=#a:pagedir><STRONG>pagedir</STRONG></A>
+<DD>  If the <A HREF=#d:page>page</A> attribute is set and applicable,
+this attribute specifies the order in which the pages are emitted.
+This is limited to one of the 8 row or column major orders.
+<DT><A NAME=d:pencolor HREF=#a:pencolor><STRONG>pencolor</STRONG></A>
+<DD>  Color used to draw the bounding box around a cluster.
+If <B>pencolor</B> is not defined, <A HREF=#d:color><B>color</B></A> is
+used. If this is not defined, <A HREF=#d:bgcolor>bgcolor</A> is used.
+If this is not defined, the default is used.
+<P>
+Note that a cluster inherits the root graph's attributes if defined.
+Thus, if the root graph has defined a <B>pencolor</B>, this will override a
+<B>color</B> or <B>bgcolor</B> attribute set for the cluster.
+<DT><A NAME=d:penwidth HREF=#a:penwidth><STRONG>penwidth</STRONG></A>
+<DD>  Specifies the width of the pen, in points, used to draw lines and curves,
+including the boundaries of edges and clusters. The value is inherited
+by subclusters.
+It has no effect on text.
+<P>
+Previous to 31 January 2008, the effect of <TT>penwidth=<I>W</I></TT>
+was achieved by including <TT>setlinewidth(<I>W</I>)</TT>
+as part of a <A HREF=#d:style><TT>style</TT></A> specification.
+If both are used, <TT>penwidth</TT> will be used.
+<DT><A NAME=d:peripheries HREF=#a:peripheries><STRONG>peripheries</STRONG></A>
+<DD>  Set number of peripheries used in polygonal shapes and cluster
+boundaries. Note that
+<A HREF=shapes.html#epsf>user-defined shapes</A> are treated as a
+form of box shape, so the default
+peripheries value is 1 and the user-defined shape will be drawn in
+a bounding rectangle. Setting <TT>peripheries=0</TT> will turn this off.
+Also, 1 is the maximum peripheries value for clusters.
+<DT><A NAME=d:pin HREF=#a:pin><STRONG>pin</STRONG></A>
+<DD>  If true and the node has a pos attribute on input, neato or fdp prevents the
+node from moving from the input position. This property can also be specified
+in the pos attribute itself (cf. the <A HREF=#d:point>point</A> type).
+<P>
+<B>Note:</B> Due to an artifact of the implementation, final coordinates
+are translated to the origin. Thus, if you look at the output coordinates
+given in the (x)dot or plain format, pinned nodes will not have the same
+output coordinates as were given on input. If this is important, a
+simple workaround is to maintain the coordinates of a pinned node. The vector
+difference between the old and new coordinates will give the translation,
+which can then be subtracted from all of the appropriate coordinates.
+<DT><A NAME=d:pos HREF=#a:pos><STRONG>pos</STRONG></A>
+<DD>  Position of node, or spline control points.
+For nodes, the position indicates the center of the node.
+On output, the coordinates are in <A HREF=#points>points</A>.
+<P>
+In neato and fdp, pos can be used to set the initial position of a node.
+By default, the coordinates are assumed to be in inches. However, the
+<A HREF=command.html#d:s>-s</A> command line flag can be used to specify
+different units. As the output coordinates are in points,
+feeding the output of a graph laid out by a Graphviz program into
+neato or fdp will almost always require the -s flag.
+<P>
+When the <A HREF=command.html#d:n>-n</A> command line flag is used with
+neato, it is assumed the positions have been set by one of the layout
+programs, and are therefore in points. Thus, <TT>neato -n</TT> can accept
+input correctly without requiring a <TT>-s</TT> flag and, in fact,
+ignores any such flag.
+<DT><A NAME=d:quadtree HREF=#a:quadtree><STRONG>quadtree</STRONG></A>
+<DD>  Quadtree scheme to use.
+<P>
+A TRUE bool value corresponds to "normal";
+a FALSE bool value corresponds to "none".
+As a slight exception to the normal interpretation of bool,
+a value of "2" corresponds to "fast".
+<DT><A NAME=d:quantum HREF=#a:quantum><STRONG>quantum</STRONG></A>
+<DD>  If <B>quantum</B> > 0.0, node label dimensions
+will be rounded to integral multiples of the quantum.
+<DT><A NAME=d:rank HREF=#a:rank><STRONG>rank</STRONG></A>
+<DD>  Rank constraints on the nodes in a subgraph.
+If <B>rank</B>="same", all nodes are placed on the same rank.
+If <B>rank</B>="min", all nodes are placed on the minimum rank.
+If <B>rank</B>="source", all nodes are placed on the minimum rank, and
+the only nodes on the minimum rank belong to some subgraph whose
+rank attribute is "source" or "min".
+Analogous criteria hold for <B>rank</B>="max" and <B>rank</B>="sink".
+(Note: the
+minimum rank is topmost or leftmost, and the maximum rank is bottommost
+or rightmost.)
+<DT><A NAME=d:rankdir HREF=#a:rankdir><STRONG>rankdir</STRONG></A>
+<DD>  Sets direction of graph layout. For example, if <B>rankdir</B>="LR",
+and barring cycles, an edge <CODE>T -> H;</CODE> will go
+from left to right. By default, graphs are laid out from top to bottom.
+<P>
+This attribute also has a side-effect in determining how record nodes
+are interpreted. See <A HREF="shapes.html#record">record shapes</A>.
+<DT><A NAME=d:ranksep HREF=#a:ranksep><STRONG>ranksep</STRONG></A>
+<DD>  In dot, this gives the desired rank separation, in inches. This is
+the minimum vertical distance between the bottom of the nodes in one
+rank and the tops of nodes in the next. If the value
+contains "equally", the centers of all ranks are spaced equally apart.
+Note that both
+settings are possible, e.g., ranksep = "1.2 equally".
+In twopi, specifies radial separation of concentric circles.
+<DT><A NAME=d:ratio HREF=#a:ratio><STRONG>ratio</STRONG></A>
+<DD>  Sets the aspect ratio (drawing height/drawing width) for the drawing.
+Note that this is adjusted before
+the <A HREF=#d:size><B>size</B></A> attribute constraints are enforced.
+<P>
+If <B>ratio</B> is numeric, it is taken as the desired aspect ratio.
+Then, if the actual aspect ratio is less than the desired ratio,
+the drawing height is scaled up to achieve the
+desired ratio; if the actual ratio is greater than that desired ratio,
+the drawing width is scaled up.
+<P>
+If <B>ratio</B> = "fill" and the <A HREF=#d:size><B>size</B></A>
+attribute is set, node positions are scaled, separately in both x
+and y, so that the final drawing exactly fills the specified size.
+<P>
+If <B>ratio</B> = "compress" and the <A HREF=#d:size><B>size</B></A>
+attribute is set, dot attempts to compress the initial layout to fit
+in the given size. This achieves a tighter packing of nodes but
+reduces the balance and symmetry. This feature only works in dot.
+<P>
+If <B>ratio</B> = "expand", the <A HREF=#d:size><B>size</B></A>
+attribute is set, and both the width and the height of the graph are
+less than the value in  <A HREF=#d:size><B>size</B></A>, node positions are scaled
+uniformly until at least
+one dimension fits <A HREF=#d:size><B>size</B></A> exactly.
+Note that this is distinct from using <A HREF=#d:size><B>size</B></A> as the
+desired size, as here the drawing is expanded before edges are generated and
+all node and text sizes remain unchanged.
+<P>
+If <B>ratio</B> = "auto", the <A HREF=#d:page><B>page</B></A>
+attribute is set and the graph cannot be drawn on a single page,
+then <A HREF=#d:size><B>size</B></A> is set to an ``ideal'' value.
+In particular, the size in a given dimension will be the smallest integral
+multiple of the page size in that dimension which is at least half the
+current size. The two dimensions are then scaled independently to the
+new size. This feature only works in dot.
+<DT><A NAME=d:rects HREF=#a:rects><STRONG>rects</STRONG></A>
+<DD>  Rectangles for fields of records, <A HREF=#points>in points</A>.
+<DT><A NAME=d:regular HREF=#a:regular><STRONG>regular</STRONG></A>
+<DD>  If true, force polygon to be regular.
+<DT><A NAME=d:remincross HREF=#a:remincross><STRONG>remincross</STRONG></A>
+<DD>  If true and there are multiple clusters, run cross
+minimization a second time.
+<DT><A NAME=d:repulsiveforce HREF=#a:repulsiveforce><STRONG>repulsiveforce</STRONG></A>
+<DD>  The power of the repulsive force used in an extended Fruchterman-Reingold
+force directed model. Values larger than 1 tend to reduce
+the warping effect at the expense of less clustering.
+<DT><A NAME=d:resolution HREF=#a:resolution><STRONG>resolution</STRONG></A>
+<DD>  This is a synonym for the <A HREF=#d:dpi>dpi</A> attribute.
+<DT><A NAME=d:root HREF=#a:root><STRONG>root</STRONG></A>
+<DD>  This specifies nodes to be used as the center of the
+layout and the root of the generated spanning tree. As a graph attribute,
+this gives the name of the node. As a node attribute (circo only), it
+specifies that the node should be used as a central node. In twopi,
+this will actually be the central node. In circo, the block containing
+the node will be central in the drawing of its connected component.
+If not defined,
+twopi will pick a most central node, and circo will pick a random node.
+<DT><A NAME=d:rotate HREF=#a:rotate><STRONG>rotate</STRONG></A>
+<DD>  If 90, set drawing orientation to landscape.
+<DT><A NAME=d:samehead HREF=#a:samehead><STRONG>samehead</STRONG></A>
+<DD>  Edges with the same head and the same <B>samehead</B> value are aimed
+at the same point on the head.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:sametail HREF=#a:sametail><STRONG>sametail</STRONG></A>
+<DD>  Edges with the same tail and the same <B>sametail</B> value are aimed
+at the same point on the tail.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:samplepoints HREF=#a:samplepoints><STRONG>samplepoints</STRONG></A>
+<DD>  If the input graph defines the <A HREF=#d:vertices><B>vertices</B></A>
+attribute, and output is dot or xdot, this gives
+the number of points used for a node whose shape is a circle or ellipse.
+It plays the same role in neato, when adjusting the layout to avoid
+overlapping nodes, and in image maps.
+<DT><A NAME=d:searchsize HREF=#a:searchsize><STRONG>searchsize</STRONG></A>
+<DD>  During network simplex, maximum number of edges with negative cut values
+to search when looking for one with minimum cut value.
+<DT><A NAME=d:sep HREF=#a:sep><STRONG>sep</STRONG></A>
+<DD>  Specifies margin to leave around nodes when removing node overlap.
+This guarantees a minimal non-zero distance between nodes.
+<P>
+If the attribute begins with a plus sign '+', an additive margin is
+specified. That is, "+w,h" causes the node's bounding box to be increased
+by w
+points on the left and right sides, and by h points on the top and bottom.
+Without a plus sign, the node is scaled by 1 + w in the x coordinate
+and 1 + h in the y coordinate.
+<P>
+If only a single number is given, this is used for both dimensions.
+<P>
+If unset but <A HREF=#d:esep>esep</A> is defined, the <tt>sep</tt> values
+will be set to the <tt>esep</tt> values divided by <tt>0.8</tt>.
+If <tt>esep</tt> is unset, the default value is used.
+<DT><A NAME=d:shape HREF=#a:shape><STRONG>shape</STRONG></A>
+<DD>  Set the shape of a node.
+<DT><A NAME=d:shapefile HREF=#a:shapefile><STRONG>shapefile</STRONG></A>
+<DD>  (Deprecated) If defined, shapefile specifies a file containing user-supplied node content.
+The <A HREF=#d:shape><B>shape</B></A> of the node is set to box.
+The image in the shapefile must be
+rectangular. The image formats supported as well as the precise semantics of
+how the file is used depends on the
+<A HREF="http://www.graphviz.org/doc/info/output.html">output format</A>.  For further details, see
+<A HREF=output.html#d:image_fmts>Image Formats</A> and
+<A HREF=http://www.graphviz.org/Documentation/html/shapehowto.html#ext_image>External PostScript files</A>.
+<P>
+There is one exception to this usage.
+If <B>shape</B> is set to "epsf", shapefile gives
+a filename containing a definition of the node in PostScript.
+The graphics defined must be contain all of the
+node content, including any desired boundaries.
+For further details, see
+<A HREF=http://www.graphviz.org/Documentation/html/shapehowto.html#ext_ps>
+External PostScript files</A>.
+<DT><A NAME=d:showboxes HREF=#a:showboxes><STRONG>showboxes</STRONG></A>
+<DD>  Print guide boxes in PostScript at the beginning of
+routesplines if 1, or at the end if 2. (Debugging)
+<DT><A NAME=d:sides HREF=#a:sides><STRONG>sides</STRONG></A>
+<DD>  Number of sides if <A HREF=#d:shape><B>shape</B></A>=polygon.
+<DT><A NAME=d:size HREF=#a:size><STRONG>size</STRONG></A>
+<DD>  Maximum width and height of drawing, in inches.
+If defined and the drawing is too large, the drawing is uniformly
+scaled down so that it fits within the given size.
+<P>
+If <TT>size</TT> ends in an exclamation point (<TT>!</TT>),
+then it is taken to be
+the desired size. In this case, if both dimensions of the drawing are
+less than <TT>size</TT>, the drawing is scaled up uniformly until at
+least one dimension equals its dimension in <TT>size</TT>.
+<P>
+Note that there is some interaction between the <B>size</B> and
+<A HREF=#d:ratio><B>ratio</B></A> attributes.
+<DT><A NAME=d:skew HREF=#a:skew><STRONG>skew</STRONG></A>
+<DD>  Skew factor for <A HREF=#d:shape><B>shape</B></A>=polygon. Positive values
+skew top of polygon to right; negative to left.
+<DT><A NAME=d:smoothing HREF=#a:smoothing><STRONG>smoothing</STRONG></A>
+<DD>  Specifies a post-processing step used to smooth out an uneven distribution
+of nodes.
+<DT><A NAME=d:sortv HREF=#a:sortv><STRONG>sortv</STRONG></A>
+<DD>  If <A HREF="#d:packmode">packmode</A> indicates an array packing,
+this attribute specifies an
+insertion order among the components, with smaller values inserted first.
+<DT><A NAME=d:splines HREF=#a:splines><STRONG>splines</STRONG></A>
+<DD>  Controls how, and if, edges are represented. If true, edges are drawn as
+splines routed around nodes; if false, edges are drawn as line segments.
+If set to "", no edges are drawn at all.
+<P>
+(1 March 2007) The values <TT>line</TT> and <TT>spline</TT> can be
+used as synonyms for <TT>false</TT> and <TT>true</TT>, respectively.
+In addition, the value <TT>polyline</TT> specifies that edges should be
+drawn as polylines.
+<P>
+By default, the attribute is unset. How this is interpreted depends on
+the layout. For dot, the default is to draw edges as splines. For all
+other layouts, the default is to draw edges as line segments. Note that
+for these latter layouts, if <TT>splines="true"</TT>, this
+requires non-overlapping nodes (cf. <A HREF=#d:overlap><B>overlap</B></A>).
+If fdp is used for layout and <TT>splines="compound"</TT>, then the edges are
+drawn to avoid clusters as well as nodes.
+<DT><A NAME=d:start HREF=#a:start><STRONG>start</STRONG></A>
+<DD>  Parameter used to determine the initial layout of nodes. If unset, the
+nodes are randomly placed in a unit square with
+the same seed is always used for the random number generator, so the
+initial placement is repeatable.
+<DT><A NAME=d:style HREF=#a:style><STRONG>style</STRONG></A>
+<DD>  Set style for node or edge. For cluster subgraph, if "filled", the
+cluster box's background is filled.
+<DT><A NAME=d:stylesheet HREF=#a:stylesheet><STRONG>stylesheet</STRONG></A>
+<DD>  A URL or pathname specifying an XML style sheet, used in SVG output.
+<DT><A NAME=d:tailURL HREF=#a:tailURL><STRONG>tailURL</STRONG></A>
+<DD>  If <B>tailURL</B> is defined, it is
+output as part of the tail label of the edge.
+Also, this value is used near the tail node, overriding any
+<A HREF=#d:URL>URL</A> value.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:tailclip HREF=#a:tailclip><STRONG>tailclip</STRONG></A>
+<DD>  If true, the tail of an edge is clipped to the boundary of the tail node;
+otherwise, the end of the edge goes to the center of the node, or the
+center of a port, if applicable.
+<DT><A NAME=d:tailhref HREF=#a:tailhref><STRONG>tailhref</STRONG></A>
+<DD>  Synonym for <A HREF=#d:tailURL>tailURL</A>.
+<DT><A NAME=d:taillabel HREF=#a:taillabel><STRONG>taillabel</STRONG></A>
+<DD>  Text label to be placed near tail of edge.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:tailport HREF=#a:tailport><STRONG>tailport</STRONG></A>
+<DD>  Indicates where on the tail node to attach the tail of the edge.
+See <A HREF=#h:undir_note>limitation</A>.
+<DT><A NAME=d:tailtarget HREF=#a:tailtarget><STRONG>tailtarget</STRONG></A>
+<DD>  If the edge has a <A HREF=#d:tailURL>tailURL</A>,
+this attribute determines 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 undefined, the value of the <A HREF=#d:target>target</A> is used.
+<DT><A NAME=d:tailtooltip HREF=#a:tailtooltip><STRONG>tailtooltip</STRONG></A>
+<DD>  Tooltip annotation attached to the tail of an edge. This is used only
+if the edge has a <A HREF=#d:tailURL>tailURL</A> attribute.
+<DT><A NAME=d:target HREF=#a:target><STRONG>target</STRONG></A>
+<DD>  If the object has a URL, this attribute determines which window
+of the browser is used for the URL.
+See <A HREF="http://www.w3.org/TR/html401/present/frames.html#adef-target">W3C documentation</A>.
+<DT><A NAME=d:tooltip HREF=#a:tooltip><STRONG>tooltip</STRONG></A>
+<DD>  Tooltip annotation attached to the node or edge. If unset, Graphviz
+will use the object's <A HREF=#d:label>label</A> if defined.
+Note that if the label is a record specification or an HTML-like
+label, the resulting tooltip may be unhelpful. In this case, if
+tooltips will be generated, the user should set a <TT>tooltip</TT>
+attribute explicitly.
+<DT><A NAME=d:truecolor HREF=#a:truecolor><STRONG>truecolor</STRONG></A>
+<DD>  If set explicitly to true or false, the value determines whether or not
+internal bitmap rendering relies on a truecolor color model or uses
+a color palette.
+If the attribute is unset, truecolor is not used
+unless there is a <A HREF=#d:shapefile>shapefile</A> property
+for some node in the graph.
+The output model will use the input model when possible.
+<P>
+Use of color palettes results in less memory usage during creation of the
+bitmaps and smaller output files.
+<P>
+Usually, the only time it is necessary to specify the truetype model
+is if the graph uses more than 256 colors.
+However, if one uses <A HREF=#d:bgcolor>bgcolor</A>=transparent with
+a color palette, font
+antialiasing can show up as a fuzzy white area around characters.
+Using <B>truecolor</B>=true avoids this problem.
+<DT><A NAME=d:vertices HREF=#a:vertices><STRONG>vertices</STRONG></A>
+<DD>  If the input graph defines this attribute, the node is polygonal,
+and output is dot or xdot, this attribute provides the
+coordinates of the vertices of the node's polygon, in inches.
+If the node is an ellipse or circle, the
+<A HREF=#d:samplepoints>samplepoints</A> attribute affects
+the output.
+<DT><A NAME=d:viewport HREF=#a:viewport><STRONG>viewport</STRONG></A>
+<DD>  Clipping window on final drawing.
+<DT><A NAME=d:voro_margin HREF=#a:voro_margin><STRONG>voro_margin</STRONG></A>
+<DD>  Factor to scale up drawing to allow margin for expansion in
+Voronoi technique. dim' = (1+2*margin)*dim.
+<DT><A NAME=d:weight HREF=#a:weight><STRONG>weight</STRONG></A>
+<DD>  Weight of edge. In dot, the heavier the weight, the shorter,
+straighter and more vertical the edge is.
+<DT><A NAME=d:width HREF=#a:width><STRONG>width</STRONG></A>
+<DD>  Width of node, in inches. This is taken as the initial, minimum width
+of the node. If <A HREF=#d:fixedsize><B>fixedsize</B></A> is true, this
+will be the final width of the node. Otherwise, if the node label
+requires more width to fit, the node's width will be increased to
+contain the label. Note also that, if the output format is dot, the
+value given to <B>width</B> will be the final value.
+<DT><A NAME=d:z HREF=#a:z><STRONG>z</STRONG></A>
+<DD>  <B>Deprecated:</B>Use <A HREF=#d:pos><B>pos</B></A> attribute, along
+with <A HREF=#d:dimen><B>dimen</B></A> and/or <A HREF=#d:dim><B>dim</B></A>
+to specify dimensions.
+<P>
+Provides z coordinate value for 3D layouts and displays. If the
+graph has <A HREF=#d:dim><B>dim</B></A> set to 3 (or more),
+neato will use a node's <B>z</B> value
+for the z coordinate of its initial position if
+its <A HREF=#d:pos><B>pos</B></A> attribute is also defined.
+<P>
+Even if no <B>z</B> values are specified in the input, it is necessary to
+declare a <B>z</B> attribute for nodes, e.g, using <TT>node[z=""]</TT>
+in order to get z values on output.
+Thus, setting <TT>dim=3</TT> but not declaring <B>z</B> will
+cause <TT>neato -Tvrml</TT> to
+layout the graph in 3D but project the layout onto the xy-plane
+for the rendering. If the <B>z</B> attribute is declared, the final rendering
+will be in 3D.
+</DL>
+<HR>
+<H1>Attribute Type Descriptions</H1>
+The following list gives the legal strings corresponding to values of
+the given types.
+<DL>
+<DT><A NAME=k:arrowType><STRONG>arrowType</STRONG></A>
+<DD><TABLE>
+<TR><TD>"normal"<TD><IMG SRC="a_normal.gif">
+<TD>"inv"<TD><IMG SRC="a_inv.gif"></TR>
+<TR><TD>"dot"<TD><IMG SRC="a_dot.gif">
+<TD>"invdot"<TD><IMG SRC="a_invdot.gif"></TR>
+<TR><TD>"odot"<TD><IMG SRC="a_odot.gif">
+<TD>"invodot"<TD><IMG SRC="a_invodot.gif"></TR>
+<TR><TD>"none"<TD><IMG SRC="a_none.gif">
+<TD>"tee"<TD><IMG SRC="a_tee.gif"></TR>
+<TR><TD>"empty"<TD><IMG SRC="a_empty.gif">
+<TD>"invempty"<TD><IMG SRC="a_invempty.gif"></TR>
+<TR><TD>"diamond"<TD><IMG SRC="a_diamond.gif">
+<TD>"odiamond"<TD><IMG SRC="a_odiamond.gif"></TR>
+<TR><TD>"ediamond"<TD><IMG SRC="a_ediamond.gif">
+<TD>"crow"<TD><IMG SRC="a_crow.gif"></TR>
+<TR><TD>"box"<TD><IMG SRC="a_box.gif">
+<TD>"obox"<TD><IMG SRC="a_obox.gif"></TR>
+<TR><TD>"open"<TD><IMG SRC="a_open.gif">
+<TD>"halfopen"<TD><IMG SRC="a_halfopen.gif"></TR>
+<TR><TD>"vee"<TD><IMG SRC="a_open.gif">
+</TABLE>
+<P>
+These are the basic set of backward-compatible arrow shapes. In addition,
+there is a grammar of <A HREF=arrows.html>arrow shapes</A>
+which can be used to describe a collection of 1,544,761 arrow combinations of the 36 varations of the primitive set of 9 arrows. The basic arrows shown
+above contain all of the primitive shapes
+(<TT>box</TT>, <TT>crow</TT>, <TT>diamond</TT>,
+<TT>dot</TT>, <TT>inv</TT>, <TT>none</tt>,
+<TT>normal</tt>, <TT>tee</TT>, <TT>vee</TT>)
+plus ones that can be derived from the grammar
+(<TT>odot</TT>, <TT>invdot</TT>, <TT>invodot</TT>,
+<TT>obox</TT>, <TT>odiamond</TT>)
+plus some supported as special cases for backward-compatibility
+(<TT>ediamond</TT>, <TT>open</TT>, <TT>halfopen</TT>,
+<TT>empty</TT>, <TT>invempty</TT>).
+<DT><A NAME=k:aspectType><STRONG>aspectType</STRONG></A>
+<DD><p>An aspect ratio, double, followed optionally by a ',' and a maximum pass
+count. If the aspect ratio is given, but no maximum pass count, the
+latter defaults to 5.
+<DT><A NAME=k:clusterMode><STRONG>clusterMode</STRONG></A>
+<DD>"local","global","none"
+<DT><A NAME=k:color><STRONG>color</STRONG></A>
+<DD>Colors can be specified using one of four formats.
+<TABLE><TR><TD>"#%2x%2x%2x"<TD>Red-Green-Blue (RGB)</TR>
+<TR><TD>"#%2x%2x%2x%2x"<TD>Red-Green-Blue-Alpha (RGBA)</TR>
+<TR><TD>H[,&#160;]+S[,&#160;]+V<TD>Hue-Saturation-Value (HSV) 0.0 <= H,S,V <= 1.0</TR>
+<TR><TD>string<TD><A HREF=colors.html>color name</A></TR></TABLE>
+The specification for the RGB and RGBA formats are the format strings used by
+<TT>sscanf</TT> to scan the color value. Thus, these values have the form
+"#RGB" or "#RGBA", where R, G, B, and A each consist of 2 hexidecimal
+digits, and can be separated by whitespace. HSV colors have the form of 3
+numbers between 0 and 1, separated by whitespace or commas.
+<P>
+String-valued color specifications are case-insensitive and interpreted
+in the context of the current color scheme, as specified by the
+<A HREF=#d:colorscheme>colorscheme</A> attribute. If this is undefined,
+the X11 naming scheme will be used.
+An initial <TT>"/"</TT> character can be used to override the use of
+the <TT>colorscheme</TT> attribute. In particular, a single initial
+<TT>"/"</TT> will cause the string to be evaluated using the default
+X11 naming. If the color value has the form <TT>"/ssss/yyyy"</TT>,
+the name <TT>yyyy</TT> is interpreted using the schema <TT>ssss</TT>.
+If the color scheme name is empty, i.e., the color has the
+form <TT>"//yyyy"</TT>, the <TT>colorscheme</TT> attribute is used.
+Thus, the forms <TT>"yyyy"</TT> and <TT>"//yyyy"</TT> are
+equivalent.
+<P>At present, Graphviz recognizes the default color scheme <TT>X11</TT>,
+and the <A HREF="http://www.personal.psu.edu/faculty/c/a/cab38/ColorBrewer/ColorBrewer_intro.html">Brewer color schemes</A>. Please note that Brewer
+color schemes are covered by this <A HREF=colors.html#brewer_license>license</A>.
+<P>
+Examples:<BR>
+<TABLE border=1>
+<TR><TH>Color<TH>RGB<TH>HSV<TH>String</TR>
+<TR><TD align=center bgcolor=#ffffff>White<TD>"#ffffff"<TD>"0.000 0.000 1.000"<TD>"white"</TR>
+<TR><TD align=center bgcolor=#000000><font color=white>Black</font><TD>"#000000"<TD>"0.000 0.000 0.000"<TD>"black"</TR>
+<TR><TD align=center bgcolor=#ff0000>Red<TD>"#ff0000"<TD>"0.000 1.000 1.000"<TD>"red"</TR>
+<TR><TD align=center bgcolor=#40e0d0>Turquoise<TD>"#40e0d0"<TD>"0.482 0.714 0.878"<TD>"turquoise"</TR>
+<TR><TD align=center bgcolor=#a0522d>Sienna<TD>"#a0522d"<TD>"0.051 0.718 0.627"<TD>"sienna"</TR>
+</TABLE>
+<P>
+Note that some output formats, e.g., <A HREF="output.html#a:mif">mif</A>,
+only support a limited number of specific colors.
+<P>
+The string value <TT>transparent</TT> can be used to indicate no color.
+This is only available in the output formats
+ps, svg, fig, vmrl, and the bitmap formats. It can be used whenever a
+color is needed but is most useful with
+the <A HREF=#d:bgcolor>bgcolor</A> attribute.
+Usually, the same effect can be achieved by setting
+<A HREF=#d:style>style</A> to <TT>invis</TT>.
+<DT><A NAME=k:colorList><STRONG>colorList</STRONG></A>
+<DD>A colon-separated list of color values: <I>C</I>(:<I>C</I>)*
+where each <I>C</I> is a <A HREF=#k:color>color</A> value.
+<DT><A NAME=k:dirType><STRONG>dirType</STRONG></A>
+<DD>For an edge <CODE>T -> H;</CODE>
+<TABLE>
+<TR><TD>"forward"<TD><IMG SRC="forward.gif">
+<TD>"back"<TD><IMG SRC="back.gif"></TR>
+<TR><TD>"both"<TD><IMG SRC="both.gif">
+<TD>"none"<TD><IMG SRC="nohead.gif"></TR>
+</TABLE>
+For undirected edges <CODE>T -- H;</CODE>, one of the nodes, usually
+the righthand one, is treated as the head for the purpose of
+interpreting "forward" and "back".
+<DT><A NAME=k:escString><STRONG>escString</STRONG></A>
+<DD>string allowing escape sequences which are replaced according
+to the context.
+For node attributes, the substring "\N" is replaced by the name of the node,
+and the substring "\G" by the name of the graph.
+For graph or cluster attributes, the substring "\G" is replaced by the
+name of the graph or cluster.
+For edge attributes, the substring "\E" is replaced by the name of the edge,
+the substring "\G" is replaced by the name of the graph or cluster,
+and the substrings "\T" and "\H" by the names of
+the tail and head nodes, respectively.
+The name of an edge is the string formed from the name of the
+tail node, the appropriate edge operator ("--" or "->") and the name of the
+head node.
+In all cases, the substring "\L" is replaced by the object's label attribute.
+<P>
+In addition, if the associated attribute is
+<A HREF=#a:label>label</A>,
+<A HREF=#a:headlabel>headlabel</A> or <A HREF=#a:taillabel>taillabel</A>,
+the escape sequences "\n", "\l" and "\r"
+divide the label into lines, centered, left-justified, and right-justified,
+respectively.
+<DT><A NAME=k:layerList><STRONG>layerList</STRONG></A>
+<DD>list of strings separated by characters from the
+<A HREF=#a:layersep>layersep</A> attribute (by default, colons,
+tabs or spaces), defining <A HREF=#a:layer>layer</A>
+names and implicitly numbered 1,2,...
+<DT><A NAME=k:layerRange><STRONG>layerRange</STRONG></A>
+<DD>layerId or layerId<B>s</B>layerId,<BR> where layerId = "all",
+a decimal integer or a <A HREF=#a:layer>layer</A> name.
+(An integer i corresponds to layer i.)
+The string <B>s</B> consists of 1 or more separator characters specified
+by the <A HREF=#a:layersep>layersep</A> attribute.
+<DT><A NAME=k:lblString><STRONG>lblString</STRONG></A>
+<DD>an <A HREF=#k:escString>escString</A>
+or an <A HREF=shapes.html#html>HTML label</A>.
+<DT><A NAME=k:outputMode><STRONG>outputMode</STRONG></A>
+<DD>"breadthfirst","nodesfirst","edgesfirst"
+These specify the order in which nodes and edges are drawn in concrete
+output. The default "breadthfirst" is the simplest, but when the graph
+layout does not avoid edge-node overlap, this mode will sometimes have
+edges drawn over nodes and sometimes on top of nodes. If the mode
+"nodesfirst" is chosen, all nodes are drawn first, followed by the
+edges. This guarantees an edge-node overlap will not be mistaken for
+an edge ending at a node. On the other hand, usually for aesthetic
+reasons, it may be desirable that all edges appear beneath nodes, even
+if the resulting drawing is ambiguous. This can be achieved by choosing
+"edgesfirst".
+<DT><A NAME=k:packMode><STRONG>packMode</STRONG></A>
+<DD>"node", "clust" , "graph" , "array[_flags][%d]"
+<P>
+The modes "node", "clust" or "graph"
+specify that the components should be packed together tightly, using
+the specified granularity.
+A value of "node" causes
+packing at the node and edge level, with no overlapping of these objects.
+This produces a layout with the least area, but it also allows interleaving,
+where a node of one component may lie between two nodes in another
+component. A value of "graph" does a packing using the bounding box of the
+component. Thus, there will be a rectangular region around a component
+free of elements of any other component.
+A value of "clust" guarantees that top-level clusters are kept intact.
+What effect a value has also depends on the layout algorithm. For
+example, neato does not support clusters, so a value of "clust" will
+have the same effect as the default "node" value.
+<P>
+The mode "array[_flags][%d]"
+indicates that the components should be packed at the
+graph level into an array of graphs. By default, the components
+are in row-major order, with the number of columns roughly the
+square root of the number of components. If the optional flags
+contains "c", then column-major order is used. Finally, if the
+optional integer suffix is used, this specifies the number of
+columns for row-major or the number of rows for column-major.
+Thus, the mode "array_c4" indicates array packing, with 4 rows,
+starting in the upper left and going down the first column, then
+down the second column, etc., until all components are used.
+<P>
+If the optional flags contains "u", this causes the insertion
+order of elements in the array to be determined by user-supplied
+values. Each component can specify its sort value by a
+non-negative integer using the <A HREF="#d:sortv">sortv</A> attribute.
+Components are
+inserted in order, starting with the one with the smallest
+sort value. If no sort value is specified, zero is used.
+<DT><A NAME=k:pagedir><STRONG>pagedir</STRONG></A>
+<DD>"BL", "BR", "TL", "TR", "RB", "RT", "LB", "LT".
+These specify the 8 row or column major orders for traversing a
+rectangular array, the first character corresponding to the major
+order and the second to the minor order. Thus, for "BL", the
+major order is from bottom to top, and the minor order is from left
+to right. This means the bottom row is traversed first, from left
+to right, then the next row up, from left to right, and so on,
+until the topmost row is traversed.
+<DT><A NAME=k:point><STRONG>point</STRONG></A>
+<DD>"%f,%f"('!') representing the point (x,y). The
+optional '!' indicates the
+node position should not change (input-only).
+<P>
+If <A HREF=#d:dim>dim</A> is 3 or more, <B>point</B> may also have
+the format "%f,%f,%f"('!') to represent the point (x,y,z).
+<DT><A NAME=k:pointf><STRONG>pointf</STRONG></A>
+<DD>"%lf,%lf" representing the point (x,y).
+<DT><A NAME=k:pointfList><STRONG>pointfList</STRONG></A>
+<DD>list of pointf, separated by spaces.
+<DT><A NAME=k:portPos><STRONG>portPos</STRONG></A>
+<DD>modifier indicating where on a node an edge should be aimed.
+It has the form <TT><I>portname</I>[:<I>compass_point</I>]</TT>
+or <TT><I>compass_point</I></TT>.
+If the first form is used, the corresponding node must either have
+<A HREF=shapes.html#record>record</A> shape with one of its fields
+having the given <I>portname</I>,
+or have an <A HREF=shapes.html#html>HTML-like label</A>, one of
+whose components has a <TT>PORT</TT> attribute set to <I>portname</I>.
+<P>
+If a compass point is used, it must have the form
+<TT>"n","ne","e","se","s","sw","w","nw","c","_"</TT>. This modifies the edge
+placement to aim for the corresponding compass point on the port or,
+in the second form where no <I>portname</I> is supplied, on the node
+itself. The compass point "c" specifies the center of the node or port.
+The compass point "_" specifies that an appropriate side of the port
+adjacent to the exterior of the node should be used, if such exists.
+Otherwise, the center is used.
+If no compass point is used with a portname, the default value is "_".
+<P>
+<P>
+This attribute can be attached to an edge using the
+<A HREF=#k:headport>headport</A> and
+<A HREF=#k:tailport>tailport</A> attributes, or as part of the
+edge description as in
+<CENTER>
+<TT>node1:port1 -> node2:port5:nw;</TT>
+</CENTER>
+<P>
+Note that it is legal to have a portname the same as one of
+the compass points. In this case, this reference will be resolved to
+the port. Thus, if node <TT>A</TT> has a port <TT>w</TT>, then
+<TT>headport=w</TT> will refer to the port and not the compass point.
+At present, in this case, there is no way to specify that the compass
+point should be used.
+<DT><A NAME=k:quadType><STRONG>quadType</STRONG></A>
+<DD>"normal", "fast", "none".
+<P>
+Using "fast" gives about a 2-4 times overall speedup compared with "normal",
+though layout quality can suffer a little.
+<DT><A NAME=k:rankType><STRONG>rankType</STRONG></A>
+<DD>"same", "min", "source", "max", "sink"
+<DT><A NAME=k:rankdir><STRONG>rankdir</STRONG></A>
+<DD>"TB", "LR", "BT", "RL", corresponding to directed graphs drawn
+from top to bottom, from left to right, from bottom to top, and from
+right to left, respectively.
+<DT><A NAME=k:rect><STRONG>rect</STRONG></A>
+<DD>"%f,%f,%f,%f"  The rectangle llx,lly,urx,ury gives the coordinates, in
+points, of the lower-left corner (llx,lly) and the upper-right corner
+(urx,ury).
+<DT><A NAME=k:shape><STRONG>shape</STRONG></A>
+<DD>A string specifying the <A HREF=shapes.html>shape</A> of a node.
+There are three
+main types of shapes :
+<A HREF=shapes.html#polygon>polygon-based</A>,
+<A HREF=shapes.html#record>record-based</A> and
+<A HREF=shapes.html#epsf>user-defined</A>.
+<DT><A NAME=k:smoothType><STRONG>smoothType</STRONG></A>
+<DD>Values are "none", "avg_dist", "graph_dist", "power_dist", "rng",
+"spring" and "triangle".
+<DT><A NAME=k:splineType><STRONG>splineType</STRONG></A>
+<DD>spline ( ';' spline )*<BR>
+<TABLE>
+<TR><TD ALIGN=right>where spline<TD>=<TD>(endp)? (startp)? point (triple)+</TR>
+<TR><TD ALIGN=right>and triple<TD>=<TD>point point point</TR>
+<TR><TD ALIGN=right>and endp<TD>=<TD>"e,%f,%f"</TR>
+<TR><TD ALIGN=right>and startp<TD>=<TD>"s,%f,%f"</TR>
+</TABLE>
+If a spline has points p<SUB>1</SUB> p<SUB>2</SUB> p<SUB>3</SUB> ... p<SUB>n</SUB>, (n = 1 (mod 3)), the points
+correspond to the control points of a B-spline from p<SUB>1</SUB> to p<SUB>n</SUB>. If startp
+is given, it touches one node of the edge, and the arrowhead
+goes from p<SUB>1</SUB> to startp. If startp is not given, p<SUB>1</SUB> touches a node.
+Similarly for p<SUB>n</SUB>  and endp.
+<DT><A NAME=k:startType><STRONG>startType</STRONG></A>
+<DD>has the syntax <TT>[<I>style</I>][<I>seed</I>]</TT>.
+<P>
+If <I>style</I> is present, it must be one of the strings <TT>"regular"</TT>,
+<TT>"self"</TT>, or <TT>"random"</TT>. In the first case, the nodes are
+placed regularly about a circle. In the second case,
+an abbreviated version of neato is run to obtain the initial layout.
+In the last case, the nodes are placed randomly in a unit square.
+<P>
+If <I>seed</I> is present, it specifies a seed for the random number
+generator. If <I>seed</I> is a positive number, this is used as the
+seed. If it is anything else,
+the current time, and possibly the process id, is used to pick a seed,
+thereby making the choice more random. In this case, the seed value
+is stored in the graph.
+<P>
+If the value is just <TT>"random"</TT>, a time-based seed is chosen.
+<P>
+Note that input positions, specified by a node's
+<A HREF=#d:pos>pos</A>
+attribute, are only used when the style is <TT>"random"</TT>.
+<DT><A NAME=k:style><STRONG>style</STRONG></A>
+<DD>styleItem ( ',' styleItem )*<BR>
+<TABLE>
+<TR><TD ALIGN=right>where styleItem<TD>=<TD>name or name'('args')'</TR>
+<TR><TD ALIGN=right>and args<TD>=<TD>name ( ',' name )*</TR>
+<TR><TD ALIGN=right>and name<TD>=<TD>[^)(, &nbsp;][^)(,]*</TR>
+</TABLE>
+Note that whitespace characters are ignored, except for names which
+can contain them. A
+name cannot contain any comma, or left or right parenthesis, and it cannot
+begin with a whitespace character.
+<P>
+At present, the recognized style names are
+"dashed", "dotted", "solid", "invis" and "bold" for nodes and edges,
+and "filled", "diagonals" and "rounded" for nodes only.
+The styles "filled" and "rounded" are recognized for clusters.
+Additional styles are available in
+device-dependent form. Style lists are passed to device drivers, which
+can use this to generate appropriate output.
+<P>
+The <TT>setlinewidth</TT> style value can be
+used for more control over the width of node borders and edges than is
+allowed by <TT>bold</TT>. This style value takes an argument, specifying the
+width of the line in <A HREF=#points>points</A>. For example, <TT>style="bold"</TT> is
+equivalent to <TT>style="setlinewidth(2)"</TT>.
+<B>The use of <TT>setlinewidth</TT> is deprecated; one should use the
+<A HREF=#d:penwidth><TT>penwidth</TT></A> attribute instead.</B>
+<DT><A NAME=k:viewPort><STRONG>viewPort</STRONG></A>
+<DD>"%lf,%lf,%lf,%lf,%lf" or  "%lf,%lf,%lf,'%s'"
+<P>
+The viewPort <TT>W,H,Z,x,y</TT> or <TT>W,H,Z,N</TT>
+specifies a viewport for the final image. The pair (W,H) gives the
+dimensions (width and height) of the final image, in
+<A HREF=#points>points</A>.
+The optional Z is the zoom factor, i.e., the image in the original layout will be
+W/Z by H/Z points in size. By default, Z is 1.
+The optional last part is either a pair (x,y) giving a position in the original layout of the
+graph, in
+<A HREF=#points>points</A>, of the center of the viewport, or the name N
+of a node whose center should used as the focus.
+By default, the focus is the center of the graph bounding box, i.e.,
+(bbx/2,bby/2), where "bbx,bby" is the
+value of the bounding box attribute <A HREF=#a:bb>bb</A>.
+<P>
+Sample values: <TT>50,50,.5,'2.8 BSD'</T> or <TT>100,100,2,450,300</TT>.
+The first will take the 100x100 point square centered on the node <TT>2.8 BSD</TT>
+and scale it down by 0.5, yielding a 50x50 point final image.
+</DL>
+</BODY>
+</HTML>

Mercurial > hg > camir-aes2014

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