3.5.1 Adding nodes to a design.
3.5.1.1The editor shall provide a facility for users to add nodes of a specified
type to their design.
3.5.1.2The sequence of actions to add a node should be as follows:
1. The user should select the type of node to be added.
2. The user should move the cursor to the approximate node position in the
diagram and indicate that the node symbol should be added at that
point.
3. The user should then drag the node symbol to its final position.
Rationale: The user is the best person to decide where to position a node on
the diagram. This approach gives the user direct control over node
type selection and positioning.