Why (some) abnormal problems are "normal"

In abnormal optimal control problems it is necessary to basically ignore the objective for certain state values in order to be able to determine the optimal control. In the past, abnormal problems were considered to be degenerated problems that did not fit to any real application. In the present paper we discuss reasons for the occurrence of abnormality. We show that abnormality can be an integral part of a meaningful problem rather than to be a sign for degeneracy.