GraphViz dirType does not seem have any effect

Question

Simple example:

digraph G {
    dirType="back"
    a -> b
}

I would expect this to make a graph with an arrow coming from b and pointed at a. Instead I get a graph with an arrow from a pointed at b, as if the dirType was not there.

I am using GraphViz 2.28 (2.28.0) for Snow Leopard.

Is there something that I'm missing, or this is a known bug?

Answer 1

Figured it out. It's supposed to be like this:

digraph G {
    edge [dir="back"]
    a -> b
}