Differential-algebraic equations (DAEs) present today the state-of-the-art
in dynamical systems arising from automated modularized modeling in almost
all areas of science and engineering. While the modeling becomes more and
more convenient, the resulting models are typically not easy to treat with
current numerical simulation, control and optimization methods. In many cases
a reformulation  of the models or even a regularization is necessary to avoid
failure of the computational methods. In this contribution we will discuss
general DAE control problems and how they can be systematically reformulated
and regularized so that the resulting system can be used in control and
optimization procedures without much further difficulty.