As described in Contouring Allocations, there are two general contour states: automatic and custom. To fully explain how contours are calculated, we have to address the variations of each state. For example, contours can be created in weekly or monthly mode, but can be shifted/extended in daily/weekly/monthly mode. PPM Pro stores how the allocation was created, and uses the information when computing changes. Each of the examples below illustrates the variations.
The examples are based on this project calendar: