Precedence relationships between activities are represented by circles connected by one or more arrows.
The dummy task is added to indicate precedence that can't be expressed using only the actual activities.
Use of ADM as a common project management practice has declined with the adoption of computer-based scheduling tools.
In addition, the precedence diagram method (PDM), or activity-on-node (AON), is often favored over ADM.[2] ADM network drawing technique the start and end of each node or event is connected to an arrow.
The event represented by the circular node consumes neither time nor resources.