We then turn to the Quicktest of the Activity 2 node. This activity starts as soon Activity 1 is finished. In order to calculate the output value of the Activity 2 node, we add its exact input value, i.e., 18.3, and its exact local value, i.e., 6.6, yielding an exact output value of 24.9. Thus, Activity 2 finishes 24.9 days after January 1., i.e., on January 25.
As already explained, the duration of a date node is calculated as the difference between its finish date, displayed in the output field, and the finish date of its predecessors. Thus, in the case of Activity 2 the duration is the difference between January 25. and January 19., that is, 6 days.
It remains then to calculate the date displayed in the input field, i.e., the start date of the activity. In general if the duration of an activity is at least one day, its start date is defined to be the day after the finish date of its predecessors. Applying this rule to our case yields January 20. as start date.
We observe that as a consequence of the applied rules, the displayed local value of a date node is not necessarily equal to its actual local value rounded off to the closest integer. In fact, in the first case the actual local value of 18.3 ended up being displayed as 19 days, while in the second case 6.6 was displayed as 6 days.
