Dot and neato are two graph layout tools that share an almost identical graph format. Dot makes layouts of directed graphs whereas neato is for undirected graphs. The format has three kinds of items: graphs, nodes, and edges. The top-level graph can be structured by introducing subgraphs, which define a subset of nodes and edges. Nodes are identified by their name. Edges are created when nodes are joined with an edge operator. Graphs, nodes, and edges can be attributed. Attributes are name-value pairs of character strings. It is also possible to define new default values for edge and node attributes (this can be seen as a primitive form of attribute inheritance). The format has a large number of predefined attributes (e.g., node shape, line style, color, and layout parameters such as weights). Application specific attributes, which are ignored by dot, can be attached as well. The following gives a code example that contains two nodes (called 'one' and 'two') that are connected with an edge. The edge is colored red.
  digraph G {
	 one -> two [ color= red ]
  }
(Quoted from ExchangeFormatBibliography) Resources: * http://www.research.att.com/sw/tools/graphviz/ ----- CategoryDataFormat | Contributions by HolgerKienle