Does DESelect Engage work on a Business Unit level or Enterprise level?

deselect engage works on a business unit (bu) level within each bu, different contact categories / campaign types / rules can be defined this also means that saturation levels for a contact that exists in multiple business units are managed per bu, where the rules for each bu are respected in bu 1, the sends received in bu 2 are not known there is currently no aggregation of sends across bus, though this may be added in the future