This document outlines rules for constructing networks and numbering events in a network. It discusses that a network must have one initial and one terminal node, with all other nodes connected on both sides. Each activity is represented by one arrow that cannot be crossed. The arrows must be straight without crossing unless unavoidable. Each event is identified by a unique number, with Fulkerson's rule describing the numbering process from the initial node outwards by deleting outgoing arrows and numbering uncovered nodes consecutively. An example network diagram and exercise are provided.