From Pluralpedia, the collaborative plurality dictionary
layering (v.)
Other formslayered (adj.)
Applies toheadmates of median systems (layered), system functions

Layering refers to how facets may front in orbital or ringed median/mixed/mediple systems/subsystems/etc. Instead of fully switching, fronting is experienced as "layering over" or "being applied to" a core identity.

This may often overlap with being monoconscious, having a shell/prism/macaron, identifying as part of a blanket self, etc., but not necessarily.