  In the two-parameter setting, we say a function belongs to the mean little
$BMO$, if its mean over any interval and with respect to any of the two
variables has uniformly bounded mean oscillation. This space has been recently
introduced by S. Pott and the author in relation with the multiplier algebra of
the product $BMO$ of Chang-Fefferman. We prove that the Cotlar-Sadosky space of
functions of bounded mean oscillation $bmo(\mathbb{T}^N)$ is a strict subspace
of the mean little $BMO$.
