  We introduce the subensemble acceptance method 2.0 (SAM-2.0) -- a procedure
to correct cumulants of a random number distribution inside a subsystem for the
effect of exact global conservation of a conserved quantity to which this
number is correlated, with applications to measurements of event-by-event
fluctuations in heavy-ion collisions. The method expresses the corrected
cumulants in terms of the cumulants inside and outside the subsystem that are
not subject to the exact conservation. The derivation assumes that all
probability distributions associated with the cumulants are peaked at the mean
values but are otherwise of arbitrary shape. The formalism reduces to the
original SAM [V. Vovchenko et al., Phys.Lett.B 811 (2020) 135868
[arXiv:2003.13905]] when applied to a coordinate space subvolume of a uniform
thermal system. As the new method is restricted neither to the uniform systems
nor to the coordinate space, it is applicable to fluctuations measured in
heavy-ion collisions at various collision energies in different momentum space
acceptances. The SAM-2.0 thus brings the experimental measurements and
theoretical calculations of event-by-event fluctuations closer together, as the
latter are typically performed without the account of exact global
conservation.
