  Let $R$ be an arbitrary subset of a commutative ring. We introduce a
combinatorial model for the set of tame frieze patterns with entries in $R$
based on a notion of irreducibility of frieze patterns. When $R$ is a ring,
then a frieze pattern is reducible if and only if it contains an entry (not on
the border) which is $1$ or $-1$. To my knowledge, this model generalizes
simultaneously all previously presented models for tame frieze patterns bounded
by $0$'s and $1$'s.
