A Gorn address (Gorn, 1967) is a method of identifying and addressing any node within a tree data structure.
This notation is often used for identifying nodes in a parse tree defined by phrase structure rules.
The Gorn address is a sequence of zero or more integers conventionally separated by dots, e.g., 0 or 1.0.1.
The root which Gorn calls * can be regarded as the empty sequence.
It is named after American computer scientist Saul Gorn.