What is a network diagram (PDM)?

Network Diagram (PDM, Precedence Diagram Method) is a graphical representation of the sequence and interrelationships between project tasks. In PDM, each task is depicted as a node (usually a rectangle), and arrows show dependencies between them — which task must be completed before the next one.

Such a diagram is useful for scheduling, identifying the critical path, and resource management. For example, if task B depends on the completion of task A, there will be an arrow from A to B.

Example of a simple PDM:

[Task A] --> [Task B] --> [Task C]

Here, it is clear that task B starts after A is completed, and C after B.