  Standard semi-classical models of decoherence do not take explicit account of
the classical information required to specify the system - environment
boundary. I show that this information can be represented as a finite set of
reference eigenvalues that must be encoded by any observer, including any
apparatus, able to distinguish the system from its environment. When the
information required for system identification is accounted for in this way,
decoherence can be described as a sequence of entanglement swaps between
reference and pointer components of the system and their respective
environments. Doing so removes the need for the a priori assumptions of ontic
boundaries required by semi-classical models.
