  We show how the formulations of low $x$ physics involving Wilson line
operators can be fully rewritten into an infinite twist TMD or GTMD framework,
respectively for inclusive and exclusive observables. This leads to a perfect
match between low $x$ physics and moderate $x$ formulations of QCD in terms of
GTMDs, TMDs, GPDs or PDFs. We derive the BFKL limit as a kinematic limit and
argue that beyond the Wandzura-Wilczek approximation, 3-body and 4-body
unintegrated PDFs should be taken into account even in this regime. Finally, we
analyze how saturation should be understood as three distinct effects:
saturation through non-linearities in the evolution equations at small $x$,
saturation through multiple interactions with slow gluons as TMD gauge links,
and saturation as the enhancement of genuine twist corrections.
