In this article we discuss Markovian term structure models in
discrete time and with continuous state space. More precisely, we
are concerned with the structural properties of such models if one
has the Markov property for a part of the forward curve. We
investigate the two cases where these parts are either a true
subset of the forward curve, including the short rate, or the
entire forward curve. For the former case we give a sufficient
condition for the term structure model to be affine. For the
latter case we provide a version of the Heath, Jarrow and Morton
drift condition. Under a Gaussian assumption a
Heath--Jarrow--Morton--Musiela type equation is derived.