  There is a wide range of stabilized finite element methods for stationary and
non-stationary convection-diffusion equations such as streamline diffusion
methods, local projection schemes, subgrid-scale techniques, and continuous
interior penalty methods to name only a few. We show that all these schemes
give rise to the same robust a posteriori error estimates, i.e. the
multiplicative constants in the upper and lower bounds for the error are
independent of the size of the convection or reaction relative to the
diffusion. Thus, the same error indicator can be used modulo higher order terms
caused by data approximation.
