The OPC Unified Architecture communication protocol is establishing itself as an integral standard for semantic communications in industrial applications, internet of things and edge communications [1]. This article presents a classification scheme for a class of aggregating systems, that is systems with the ability to integrate information from other, distributed devices into their own namespaces [2]. The functions and capabilities of these systems encountered in practice vary greatly; being applied to systems ranging from fieldbus gateways [3] to intelligent information processing nodes for harmonizing information models [4]. This article first introduces a general architecture model for aggregating systems and proceeds to detail functionality and Cross-Cutting Concerns that effect these systems. Finally, an existing solution is analyzed as case studies using the established classification system.