It is best to understand what part of the architecture one is working on in order to best choose the right type of infrastructure required. Conceptually it starts at the bottom, where “EO” stands for equipment outlet, or in the industrial space the ‘edge device’ (for example a sensor or drive). Then there are two, and sometimes three, sets of patching systems or “distributors”, such as a consolidation of Ethernet nodes in a common spot either into DIN mount industrial switches (such as a Zone enclosure) or 19” switches for higher port count requirements (such as an Industrial distribution frame). These distribution systems are on the way up to the industrial network core at the top, such as a Data Center for the plant floor where things like the DMZ (the demilitarized zone) lives – the separation of the Office and Plant floor space. From the bottom up these are depicted as “DA” (Distributor A), “DB” (Distributor B) and “DC” (Distributor C). Distributor C is the patching collocated with the actual network core equipment. The cabling subsystems also start at the bottom and move up toward the network core. The link that connects the equipment outlet is “Cabling Subsystem 1”, then moving up there is Subsystem 2 and Subsystem 3 attaching the network core. Each of these areas depict different areas of the plant floor and may require different types of solutions (some industrial rated and others standard enterprise type of solutions). For example - Subsystem 1 is usually copper and subsystem 2 and 3 are usually some kind of fiber. The reason fiber links are broken into two subsystems is that these may be completely different kinds of fiber links depending on distance and environments.