Blocktree/doc/Book/example_bt.gv

digraph {
    none [shape = none, label = ""]
    root [shape = folder, label = ""];
    phone [shape = invtriangle, label = ""];
    editor [shape = circle, label = ""];
    laptop [shape = invtriangle, label = ""];
    viewer [shape = circle, label = ""];
    docs [shape = folder, label = ""];
    resignation [shape = box, label = ""];
    contract [shape = box, label = ""];
    avatar [shape = box, label = ""];
    none -> root [label = "<root>"]
    root -> phone [label = "phone"];
    phone -> viewer [label = "<editor1>"];
    root -> laptop [label = "laptop"];
    laptop -> editor [label = "<editor2>"];
    root -> docs [label = "docs"];
    docs -> resignation [label = "resignation.docx"];
    docs -> contract [label = "contract.docx"];
    root -> avatar [label = "avatar.usd"];
}