  We analyze the range of applicability of the high energy Reggeon Field Theory
$H_{RFT}$ derived in [1]. We show that this theory is valid as long as at any
intermediate value of rapidity $\eta$ throughout the evolution at least one of
the colliding objects is dilute. Importantly, at some values of $\eta$ the
dilute object could be the projectile, while at others it could be the target,
so that $H_{RFT}$ does not reduce to either $H_{JIMWLK}$ or $H_{KLWMIJ}$. When
both objects are dense, corrections to the evolution not accounted for in [1]
become important. The same limitation applies to other approaches to high
energy evolution available today, such as for example [3] and [4]. We also show
that, in its regime of applicability $H_{RFT}$ can be simplified. We derive the
simpler version of $H_{RFT}$ and in the large $N_c$ limit rewrite it in terms
of the Reggeon creation and annihilation operators. The resulting $H_{RFT}$ is
explicitly self dual and provides the generalization of the Pomeron calculus
developed in [4] by including higher Reggeons in the evolution. It is
applicable for description of `large' Pomeron loops, namely Reggeon graphs
where all the splittings occur close in rapidity to one dilute object
(projectile), while all the merging close to the other one (target).
Additionally we derive, in the same regime expressions for single and double
inclusive gluon production (where the gluons are not separated by a large
rapidity interval) in terms of the Reggeon degrees of freedom.
