layered-structure, hierarchical-structure, stratified-structure, multi-level-structure, tiered-system, layered-system, hierarchical-system, stratified-system, multi-tiered-structure, multi-tiered-syst... [more]
layered-structure, hierarchical-structure, stratified-structure, multi-level-structure, tiered-system, layered-system, hierarchical-system, stratified-system, multi-tiered-structure, multi-tiered-syst... [more]