[computer-go] What is All-as-first-heuristic?

[Chrilly]

>
> Previously I never experimented with the All-as-first-heuristic but I ran 
> some
> tests with a simple MC-search some days ago and became convinced that it 
> was
> indeed useful. The trick seems to be to strike a balance between move 
> ordering
> and move selection. The heuristic is very good for move ordering

Can someone me please explain what is All-as-first-heuristic? If possible 
with a link to an article where the concepts are explained/defined.

IChrilly