  We establish that QED3 can possess a critical number of flavours, N_f^c,
associated with dynamical chiral symmetry breaking if, and only if, the fermion
wave function renormalisation and photon vacuum polarisation are homogeneous
functions at infrared momenta when the fermion mass function vanishes. The Ward
identity entails that the fermion-photon vertex possesses the same property and
ensures a simple relationship between the homogeneity degrees of each of these
functions. Simple models for the photon vacuum polarisation and fermion-photon
vertex are used to illustrate these observations. The existence and value of
N_f^c are contingent upon the precise form of the vertex but any discussion of
gauge dependence is moot. We introduce an order parameter for confinement.
Chiral symmetry restoration and deconfinement are coincident owing to an abrupt
change in the analytic properties of the fermion propagator when a nonzero
scalar self-energy becomes insupportable.
