This paper studies chaos in the sense of Devaney for a class of two-dimensional time-varying generalized symbol systems of the form [Formula: see text] where [Formula: see text] for [Formula: see text], [Formula: see text] is an integer, [Formula: see text] and [Formula: see text] are two well-defined functions. By introducing a more restrictive concept of chaos in the sense of Devaney, some sufficient conditions for this system to be completely chaotic in the sense of Devaney are derived.