  We recall the origin of angular ordering of soft parton emission in the
region of small $x$ and show that this coherent structure can be detected in
associated distributions. For structure functions at small $x$ and at fixed
transverse momentum the angular ordering is masked because of the complete
inclusive cancellations of collinear singularities for \xt0. Therefore, in this
case the dependence on the hard scale is lost and the angular ordered region
becomes equivalent to multi-Regge region in which all transverse momenta are of
the same order. In this limit one derives the BFKL equation. In general such a
complete cancellation does not hold for the associated distributions at small
$x$. The calculation, which requires an analysis without any collinear
approximation, is done by extending to small $x$ the soft gluon factorization
techniques largely uses in the region of large $x$. Since one finds angular
ordering in the both regions of small and large $x$, one can formulate a
unified evolution equation for the structure function, a unified coherent
branching and jet algorithm which allows the calculation of associated
distributions in all $x$ regions. Such a unified formulation valid for all $x$
is presented and compared with usual treatments. In particular we show that the
associated distributions at small $x$ are sensitive to coherence. By replacing
angular ordering with the multi-Regge region one neglects large singular
contributions in the associated distributions.
