Abstract: A substrate installation unit for installing with other substrate installation units, in particular of the same type, for covering a substrate, wherein the substrate installation unit comprises a substrate-side attachment structure, which is designed for attaching to the substrate; and a plug connection structure, facing away from the substrate, for releasably plug connecting, in particular with a formation of a snap-in plug connection with a correspondingly designed plug connection structure of a surface installation unit, which comprises a utilization structure.

Abstract: Surface laying unit (100) for laying with other surface laying units (100) on an underlying surface (300), wherein the surface laying unit (100) has a useful layer (102) and a connecting structure (104) which is provided directly on an underside of the useful layer (102) and which is designed for connecting to the underlying surface (300).

Abstract: Surface laying unit (100) for laying with other surface laying units (100) on an underlying surface (300), wherein the surface laying unit (100) has a useful layer (102) and a connecting structure (104) which is provided directly on an underside of the useful layer (102) and which is designed for connecting to the underlying surface (300).