dir

type: dirType, default: forward (directed) , none (undirected)

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.

digraph {
  A->B [dir=forward]
  C->D [dir=back]
  E->F [dir=both]
  G->H [dir=none]
}

• Edges

Search the Graphviz codebase for "dir"