The Completed Flag column is used in a number of BrightWork lists to exclude completed items from certain BrightWork web parts (for example Project List, My Work and List Metrics). The column uses a formula similar to the below to achieve this:
=[Status Code]="3"
You can edit the formula to widen or narrow the parameters that trigger the Completed Flag.
For example, suppose you wanted the My Work report to also exclude projects whose status was (5) Cancelled. To do this you would edit the Completed Flag field formula on the Project Summary list so that it included the value.
The formula would change from:
=[Status Code]="3"
to:
=OR([Status Code]="3", [Status Code]="5")