  Strong typicality and the Markov lemma have been used in the proofs of
several multiterminal source coding theorems. Since these two tools can be
applied to finite alphabets only, the results proved by them are subject to the
same limitation. Recently, a new notion of typicality, namely unified
typicality, has been defined. It can be applied to both finite or countably
infinite alphabets, and it retains the asymptotic equipartition property and
the structural properties of strong typicality. In this paper, unified
typicality is used to derive a version of the Markov lemma which works on both
finite or countably infinite alphabets so that many results in multiterminal
source coding can readily be extended. Furthermore, a simple way to verify
whether some sequences are jointly typical is shown.
