A pcb-rnd config file, (or document for short) has a single root node whose name must be li:pcb-rnd-conf-v1 - this is the signature of the -document. It is a flat list of one or more config root/ subtrees. +document. It is a flat list of one or more config root/ subtrees. TODO: is this really a list or a hash?
Each config root is a partial description of the