# Graph Attributes

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.

All GraphViz attributes are specified by name-value pairs. Thus, to set the fillcolor of a node `abc`, one would use

`abc [fillcolor = red]`

Similarly, to set the arrowhead style of an edge `abc -> def`, one would use

`abc -> def [arrowhead = diamond]`

Further details concerning the setting of attributes can be found in the description of the DOT language.

Note: Some attributes, such as dir or arrowtail, are ambiguous when used in DOT 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 DOT parser will assign the left node as the tail node and the right node as the head. For example, the edge `A -- B` will have tail `A` and head `B`. It is the user's responsibility to handle such edges consistently. If the edge appears later, in the format

`B -- A [taillabel = "tail"]`

the drawing will attach the tail label to node `A`. 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 dir, arrowtail or arrowhead attributes.

The tools accept standard C representations for int and double types. For the bool 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 arrowType, color, pointf and rankdir. Legal values for these types are given at the end.

In the Used By 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.

Name | Used By | Type | Default | Minimum | Notes
--- | --- | --- | --- | --- | ---
Damping | G | double | 0.99 | 0.0 | neato only
URL | ENGC | escString string |  |  | svg, postscript, map only
arrowhead | E | arrowType | normal |  |
arrowsize | E | double | 1.0 | 0.0 |
arrowtail | E | arrowType | normal |  |
bb | G | rect |  |  | write only
bgcolor | GC | color |  |  |
bottomlabel | N | string | "" |  |
center | G | bool | false |  |
clusterrank | G | clusterMode | local |  | dot only
color | ENC | color | black |  |
comment | ENG | string | "" |  |
compound | G | bool | false |  | dot only
concentrate | G | bool | false |  | dot only
constraint | E | bool | true |  | dot only
decorate | E | bool | false |  |
defaultdist | G | double | 1+(avg. len)*sqrt(|V|) | epsilon | neato only
dim | G | int | 2 | 2 | neato only
dir | E | dirType | forward(directed) none(undirected) |  |
distortion | N | double | 0.0 | -100.0 |
epsilon | G | double | (.0001 * # nodes) |  | neato only
fillcolor | NC | color | lightgrey(nodes) black(clusters) |  |
fixedsize | N | bool | false |  |
fontcolor | ENGC | color | black |  |
fontname | ENGC | string | "Times-Roman" |  |
fontpath | G | string | system-dependent |  |
fontsize | ENGC | double | 14.0 | 1.0 |
group | N | string | "" |  | dot only
headURL | E | escString | "" |  | map only
headclip | E | bool | true |  |
headhref | E | escString | "" |  | map only
headlabel | E | lblString | "" |  |
headport | E | portPos | center |  |
headtarget | E | escString |  |  | map only
headtooltip | E | escString | "" |  | cmap only
height | N | double | 0.5 | 0.02 |
href | E | escString | "" |  | svg, postscript, map only
label | ENGC | lblString | "\N" (nodes) "" (otherwise) |  |
labelangle | E | double | -25.0 | -180.0 |
labeldistance | E | double | 1.0 | 0.0 |
labelfloat | E | bool | false |  |
labelfontcolor | E | color | black |  |
labelfontname | E | string | "Times-Roman" |  |
labelfontsize | E | double | 11.0 | 1.0 |
labeljust | GC | string | "c" |  |
labelloc | GC | string | "t"(clusters) "b"(root graphs) |  |
layer | EN | layerRange | "" |  |
layers | G | layerList | "" |  |
layersep | G | string | " | \t" |
len | E | double | 1.0 |  | neato only
lhead | E | string | "" |  | dot only
lp | EGC | point |  |  | write only
ltail | E | string | "" |  | dot only
margin | G | double pointf |  |  |
maxiter | G | int | MAXINT |  | neato only
mclimit | G | double | 1.0 |  | dot only
mindist | G | double | 1.0 | 0.0 | circo only
minlen | E | int | 1 | 0 | dot only
model | G | string | "" |  | neato only
nodesep | G | double | 0.25 | 0.02 | dot only
normalize | G | bool | false |  | not dot
nslimit nslimit1 | G | double |  |  | dot only
ordering | G | string | "" |  | dot only
orientation | N | double | 0.0 | 360.0 |
orientation | G | string | "" |  |
outputorder | G | outputMode | breadthfirst |  |
overlap | G | string bool | "" |  | not dot
pack | G | bool int | false |  | not dot
packmode | G | packMode | node |  | not dot
page | G | pointf |  |  |
pagedir | G | pagedir | BL |  |
pencolor | C | color | black |  |
peripheries | NC | int | shape default(nodes) 1(clusters) | 0 |
pin | N | bool | false |  | neato only
pos | EN | point splineType |  |  |
quantum | G | double | 0.0 | 0.0 |
rank | S | rankType |  |  | dot only
rankdir | G | rankdir | TB |  | dot only
ranksep | G | double | 0.5(dot) 1.0(twopi) | 0.02 | twopi, dot only
ratio | G | double string |  |  |
rects | N | rect |  |  | write only
regular | N | bool | false |  |
remincross | G | bool | false |  | dot only
resolution | G | double | 0.96 |  | svg only
root | GN | string bool | ""(graphs) false(nodes) |  | circo, twopi only
rotate | G | int | 0 |  |
samehead | E | string | "" |  | dot only
sametail | E | string | "" |  | dot only
samplepoints | G | int | 8 |  |
searchsize | G | int | 30 |  | dot only
sep | G | double | 0.01 |  | not dot
shape | N | shape | ellipse |  |
shapefile | N | string | "" |  |
showboxes | ENG | int | 0 | 0 | dot only
sides | N | int | 4 | 0 |
size | G | pointf |  |  |
skew | N | double | 0.0 | -100.0 |
splines | G | bool | false |  | not dot
start | G | string int | "" |  | neato only
style | ENC | style |  |  |
stylesheet | G | string | "" |  | svg only
tailURL | E | escString | "" |  | map only
tailclip | E | bool | true |  |
tailhref | E | escString | "" |  | map only
taillabel | E | lblString | "" |  |
tailport | E | portPos | center |  |
tailtarget | E | escString |  |  | map only
tailtooltip | E | escString | "" |  | cmap only
target | ENGC | escString string |  |  | svg, map only
tooltip | NE | escString | "" |  | cmap only
toplabel | N | string | "" |  |
truecolor | G | bool |  |  | bitmap output only
vertices | N | pointfList |  |  | write only
voro_margin | G | double | 0.05 | 0.0 | not dot
weight | E | double | 1.0 | 0(dot) 1(neato) |
width | N | double | 0.75 | 0.01 |
z | N | double | 0.0 | -MAXFLOAT -1000 |

# Attribute Descriptions

Damping
  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.
URL
  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.

  The active area for a node or cluster is its bounding box. For edges, the active areas are small circles where the edge contacts its head and tail nodes. These areas 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. Note, however, that if the edge has a headURL attribute, it is this value that is used near the head node and on the head label, if defined. The similar restriction holds when tailURL is defined.

  The URL of the root graph is only treated as an escString if the output format is cmap.

arrowhead
  Style of arrowhead on the head node of an edge. See also the dir attribute, and a limitation.
arrowsize
  Multiplicative scale factor for arrowheads.
arrowtail
  Style of arrowhead on the tail node of an edge. See also the dir attribute, and a limitation.
bb
  Bounding box of drawing in integer points.
bgcolor
  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 style, the cluster's fillcolor will overlay the background color.
bottomlabel
  Additional label near bottom of nodes of shape M*.
center
  If true, the drawing is centered in the output canvas.
clusterrank
  Mode used for handling clusters. If clusterrank 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 label 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.
color
  Basic drawing color for graphics.
comment
  Comments are inserted into output. Device-dependent
compound
  If true, allow edges between clusters. (See lhead and ltail below.)
concentrate
  If true, use edge concentrators.
constraint
  If false, the edge is not used in ranking the nodes. For example, in the graph

        digraph G {
          a -> c;
          a -> b;
          b -> c [constraint=false];
        }

  the edge `b -> c` does not add a constraint during rank assignment, so the only constraints are that a be above b and c, yielding the graph:
decorate
  If true, attach edge label to edge by a 2-segment polyline, underlining the label, then going to the closest point of spline.
defaultdist
  This specifies the distance between nodes in separate connected components. If set too small, connected components may overlap. Only applicable if pack=false.
dim
  Set the number of dimensions used for the layout. The maximum value allowed is 10.
dir
  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 arrowhead and arrowtail attributes. See limitation.
distortion
  Distortion factor for shape=polygon. Positive values cause top part to be larger than bottom; negative values do the opposite.
epsilon
  Terminating condition. If the length squared of all energy gradients are < epsilon, the algorithm stops.
fillcolor
  Color used to fill the background of a node or cluster. If fillcolor is not defined, color is used. (For clusters, if color is not defined, bgcolor is used.) If this is not defined, the default is used, except for shape=point or when the output format is MIF, which use black by default.

  Note that a cluster inherits the root graph's attributes if defined. Thus, if the root graph has defined a fillcolor, this will override a color or bgcolor attribute set for the cluster.

fixedsize
  If true, the node size is specified by the values of the width and height attributes only and is not expanded to contain the text label.
fontcolor
  Color used for text.
fontname
  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.

  The GraphViz tools use True Type fonts for bitmap output. If you specify `fontname=schlbk`, the tool will look for a file named `schlbk.ttf` in one of the directories specified by the fontpath attribute.

fontpath
  Directory list used by libgd to search for bitmap fonts. If fontpath is not set, the environment variable `DOTFONTPATH` is checked. If that is not set, `GDFONTPATH` is checked. If not set, libgd uses its compiled-in font path. Note that fontpath is an attribute of the root graph.
fontsize
  Font size, in points, used for text.
group
  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.
headURL
  For the output format imap or cmap, if headURL is defined, it is output as part of the head label of the edge. See limitation.
headclip
  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.
headhref
  Synonym for headURL.
headlabel
  Text label to be placed near head of edge. See limitation.
headport
  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 limitation.
headtarget
  If the edge has a headURL, 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 target is used.
headtooltip
  Tooltip annotation attached to the head of an edge. This is used only if the edge has a headURL attribute.
height
  Height of node, in inches. This is taken as the initial, minimum height of the node. If fixedsize 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 height will be the final value.
href
  Synonym for URL.
label
  Text label attached to objects. If a node's shape is record, then the label can have a special format which describes the record layout.
labelangle
  Angle, in degrees, that the headlabel(taillabel) is rotated from the angle the edge makes incident with the head(tail) node, respectively.
labeldistance
  Multiplicative scaling factor adjusting the distance that the headlabel(taillabel) is the from head(tail) node.
labelfloat
  If true, allows edge labels to be less constrained in position. In particular, it may appear on top of other edges.
labelfontcolor
  Color used for headlabel and taillabel.
labelfontname
  Font used for headlabel and taillabel.
labelfontsize
  Font size, in points, used for headlabel and taillabel.
labeljust
  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 labeljust to "l", the subgraph inherits this value.
labelloc
  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 labelloc to "b", the subgraph inherits this value.
layer
  Specifies layers in which the node or edge is present.
layers
  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 How to use drawing layers (overlays).
layersep
  Specifies the separator characters used to split the layers attribute into a list of layer names.
len
  Preferred edge length, in inches.
lhead
  Logical head of an edge. When compound is true, if lhead is defined and is the name of a cluster containing the real head, the edge is clipped to the boundary of the cluster. See limitation.
lp
  Label position, in points.
ltail
  Logical tail of an edge. When compound is true, if ltail is defined and is the name of a cluster containing the real tail, the edge is clipped to the boundary of the cluster. See limitation.
margin
  Set x and y margins of canvas, in inches. In first case, both margins are set equal to the given value.
maxiter
  Sets the number of iterations used.
mclimit
  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.
mindist
  Specifies the minimum separation between all nodes.
minlen
  Minimum edge length (rank difference between head and tail).
model
  If "circuit", use circuit resistance model to compute dissimilarity values; otherwise, use shortest path model.
nodesep
  Minimum space between two adjacent nodes in the same rank, in inches.
normalize
  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.
nslimit ,
nslimit1
  Used to set number of iterations in network simplex applications. nslimit is used in computing node x coordinates, nslimit1 for ranking nodes. If defined, # iterations = nslimit(1) * # nodes; otherwise, # iterations = MAXINT.
ordering
  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.
orientation
  Angle, in degrees, used to rotate node shapes.
orientation
  If "[lL]*", set graph orientation to landscape Used only if rotate is not defined.
outputorder
  Specify order in which nodes and edges are drawn.
overlap
  If "scale", remove node overlaps by scaling; if converts to false, remove node overlaps by the Voronoi technique; otherwise, leave overlaps. This is not yet available in circo.
pack
  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 tightly. If pack has an integral value, this is used as the size (in points) 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 packmode attribute. For layouts which always do packing, such a twopi, the pack attribute is just used to set the margin.
packmode
  This indicates the granularity and method used for packing (cf. packMode). Note that defining packmode will automatically turn on packing as though one had set pack=true.
page
  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 pagedir order.
pagedir
  If the page 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.
pencolor
  Color used to draw the bounding box around a cluster. If pencolor is not defined, color is used. If this is not defined, bgcolor is used. If this is not defined, the default is used.

  Note that a cluster inherits the root graph's attributes if defined. Thus, if the root graph has defined a pencolor, this will override a color or bgcolor attribute set for the cluster.

peripheries
  Set number of peripheries used in polygonal shapes and cluster boundaries. Note that user-defined shapes 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 `peripheries=0` will turn this off. Also, 1 is the maximum peripheries value for clusters.
pin
  If true and the node has a pos attribute on input, neato prevents the node from moving from the input position. This property can also be specified in the pos attribute itself (cf. the point type).
pos
  Position of node, or spline control points, in points. In neato, pos can be used to set initial position of a node. Concerning this, see the -s command line flag.
quantum
  If quantum > 0.0, node label dimensions will be rounded to integral multiples of the quantum.
rank
  Rank constraints on the nodes in a subgraph. If rank="same", all nodes are placed on the same rank. If rank="min", all nodes are placed on the minimum rank. If rank="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 rank="max" and rank="sink". (Note: the minimum rank is topmost or leftmost, and the maximum rank is bottommost or rightmost.)
rankdir
  Sets direction of graph layout. If rankdir="LR", the graph is laid out from left to right, i.e., directed edges tend to go from left to right. By default, graphs are laid out from top to bottom.
ranksep
  In dot, this the gives 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.
ratio
  Sets the aspect ratio (drawing height/drawing width) for the drawing. Note that this is adjusted before the size attribute constraints are enforced.

  If ratio 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.

  If ratio = "fill" and the size attribute is set, node positions are scaled, separately in both x and y, so that the final drawing exactly fills the specified size.

  If ratio = "compress" and the size 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.

  If ratio = "auto", the page attribute is set and the graph cannot be drawn on a single page, then size 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.

rects
  Rectangles for fields of records, in points.
regular
  If true, force polygon to be regular.
remincross
  If true and there are multiple clusters, run cross minimization a second time.
resolution
  This specifies the expected number of pixels per inch on a display. It is used to guarantee that dimensions in the output correspond to the correct number of points or inches.
root
  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.
rotate
  If 90, set drawing orientation to landscape.
samehead
  Edges with the same head and the same samehead value are aimed at the same point on the head. See limitation.
sametail
  Edges with the same tail and the same sametail value are aimed at the same point on the tail. See limitation.
samplepoints
  If the input graph defines the vertices attribute, and output is dot or xdot, this give the number of points used to represent circles and ellipses. It plays the same role in neato, when adjusting the layout to avoid overlapping nodes.
searchsize
  During network simplex, maximum number of edges with negative cut values to search when looking for one with minimum cut value.
sep
  Fraction to increase polygons (multiply coordinates by 1 + sep) for purposes of determining overlap. Guarantees a minimal non-zero distance between nodes.
shape
  Set the shape of a node.
shapefile
  If non-empty, when output format is ps* or svg* and shape is set to "espf", taken as a filename containing a device-dependent description of a node's shape. If non-empty for bitmap output (gif, jpeg, png, etc.) and shape set to "custom", taken as the URL for a file containing the bitmap image for the node. For files on the local machine, the URL begins with "file://". For remote files, graphviz must have been configured to use a command such as curl to retrieve the files remotely.
showboxes
  Print guide boxes in PostScript at the beginning of routesplines if 1, or at the end if 2. (Debugging)
sides
  Number of sides if shape=polygon.
size
  Maximum width and height of drawing, inches. If defined and the drawing is too large, the drawing is uniformly scaled down so that it fits within the given size. Note that there is some interaction between the size and ratio attributes.
skew
  Skew factor for shape=polygon. Positive values skew top of polygon to right; negative to left.
splines
  If true, draw edges as splines. This requires non-overlapping nodes (cf. overlap).
start
  Parameter used to determine the initial layout of nodes. By default, nodes are randomly placed in a square whose sides have length (# nodes). The same seed is always used for the random number generator, so the initial placement is repeatable. If start converts to an integer, this is used as a seed value for the random number generator. If start is "regular", the nodes are placed regularly about a circle. Finally, if start is defined but is not one of the above cases, the current time is used to pick a seed.
style
  Set style for node or edge. For cluster subgraph, if "filled", the cluster box's background is filled.
stylesheet
  A URL or pathname specifying an XML style sheet, used in SVG output.
tailURL
  When the output format is imap or cmap, if tailURL is defined, it is output as part of the tail label of the edge. See limitation.
tailclip
  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.
tailhref
  Synonym for tailURL.
taillabel
  Text label to be placed near tail of edge. See limitation.
tailport
  Indicates where on the tail node to attach the tail of the edge. See limitation.
tailtarget
  If the edge has a tailURL, 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 target is used.
tailtooltip
  Tooltip annotation attached to the tail of an edge. This is used only if the edge has a tailURL attribute.
target
  If the object has a URL, 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.
tooltip
  Tooltip annotation attached to the node or edge. This is used only if the object has a URL attribute.
toplabel
  Additional label near top of nodes of shape M*.
truecolor
  If set explicitly to true or false, the value determines whether or not bitmap output relies on a truecolor color model. If the attribute is unset, then automatic selection is used. Automatic selection uses indexed color, unless there is a shapefile property for any node in the graph.
vertices
  If the input graph defines this attribute, the node is polynomial, and output is dot or xdot, this attribute provides the coordinates of the vertices of the node's polynomial, in inches. If the node is an ellipse or circle, the samplepoints attribute affects the output.
voro_margin
  Factor to scale up drawing to allow margin for expansion in Voronoi technique. dim' = (1+2*margin)*dim.
weight
  Weight of edge. In dot, the heavier the weight, the shorter, straighter and more vertical the edge is. In neato, the heavier the weight, the more neato will try to place the end points so that the length of the edge is len.
width
  Width of node, in inches. This is taken as the initial, minimum width of the node. If fixedsize 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 width will be the final value.
z
  Provides z coordinate for the node when output format is VRML.

# Attribute Type Descriptions

The following list gives the legal strings corresponding to values of the given types.

arrowType

  "normal" |
  | "inv" | "dot" |  | "invdot" |
  "odot" |  | "invodot" |
  "none" |  | "tee" |
  "empty" |  | "invempty" |
  "diamond" |  | "odiamond" |
  "ediamond" |  | "crow" |
  "box" |  | "obox" |
  "open" |  | "halfopen" |

  These are the basic arrow shapes. In addition, there is a grammar of arrow shapes which can be used to describe a collection of 1200 arrow shapes as modifications of a primitive set of 9 arrows. The basic arrows shown above contain all of the primitive shapes (e.g., `normal`, `box`, `tee`, etc.) plus ones that can be derived from the grammar (e.g., `ediamond`, `inv`).

clusterMode
  "local","global","none"
color

  "#%2x%2x%2x" | RGB
  "#%2x%2x%2x%2x" | RGBA
  H[, ]+S[, ]+V | 0.0 <= H,S,V <= 1.0
  string | color name

dirType
  For an edge `T -> H;`

  "forward" |  | "back" |
  "both" |  | "none" |

  For undirected edges `T -- H;`, one of the nodes, usually the righthand one, is treated as the head for the purpose of interpreting "forward" and "back".
escString
  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 "\N" is replaced by the name of the edge, 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 addition, if the associated attribute is label, headlabel or taillabel, the escape sequences "\n", "\l" and "\r" divide the label into lines, centered, left-justified, and right-justified, respectively.

layerList
  list of strings separated by characters from the layersep attribute (by default, colons, tabs or spaces), defining layer names and implicitly numbered 1,2,...
layerRange
  layerId or layerIdslayerId,
  where layerId = "all", a decimal integer or a layer name. (An integer i corresponds to layer i.) The string s consists of 1 or more separator characters specified by the layersep attribute.
lblString
  an escString or an HTML label.
outputMode
  "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".
packMode
  "node","clust","graph" These specify the granularity of packing connected components when the pack attribute is true. A value of "node" causes packing at the node and edge label, 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.
pagedir
  "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.
point
  "%d,%d"('!') representing the point (x,y). The optional '!' indicates the node position should not change (input-only).
pointf
  "%lf,%lf" representing the point (x,y).
pointfList
  list of pointf, separated by spaces.
portPos
  ":n",":ne",":e",":se",":s",":sw",":w",":nw" These correspond to the obvious compass points on the node.
rankType
  "same", "min", "source", "max", "sink"
rankdir
  "LR". Any other value corresponds to a top-down layout.
rect
  "%d,%d,%d,%d" The rect llx,lly,urx,ury gives the coordinates, in points, of the lower-left corner (llx,lly) and the upper-right corner (urx,ury).
shape
  A string specifying the shape of a node. There are three main types of shapes : polygon-based, record-based and user-defined.
splineType
  spline ( ';' spline )*

  where spline | = | (endp)? (startp)? point (triple)+
  and triple | = | point point point
  and endp | = | "e,%d,%d"
  and startp | = | "s,%d,%d"

  If a spline has points p1 p2 p3 ... pn, (n = 1 (mod 3)), the points correspond to the control points of a B-spline from p1 to pn. If startp is given, it touches one node of the edge, and the arrowhead goes from p1 to startp. If startp is not given, p1 touches a node. Similarly for pn and endp.
style
  styleItem ( ',' styleItem )*

  where styleItem | = | name or name'('args')'
  and args | = | name ( ',' name )*
  and name | = | [^)(, ][^)(,]*

  At present, the recognized style names comprise "dashed", "dotted", "solid", "invis" and "bold" for nodes and edges, and "filled", "diagonals" and "rounded" for nodes only. Additional styles are available in device-dependent form. Style lists are passed to device drivers, which can use this to generate appropriate output.

  Note that, at present, "rounded" cancels "filled", except for circles and ellipses. This holds for the Mrecord shape, which is rounded by definition.