| Changes
In TIA-568 Standard For Premises Cabling Systems - RESCINDED! In 2011 TIA changed the nomenclature of structured cabling systems. Many years later, the earlier terms which came from a century of use in the telephone system are still preferred by many in the industry. The terminology in TIA-568-C.0, Generic Telecommunications Cabling For Customer Premises, was changed to a more generic (i.e. not traditional telecom) nomenclature. Unfortunately, all this proved to be confusing and unpopular, so in 2025, after 14 years, TIA returned to the original terms from telecom jargon.  For historical reasons - and the fact that some documents may still have the TIA wording, here is the FOA interpretation in CAPS and diagrams for explanation of the rescinded terms. The traditional terms for the location of the ends of the cabling or interconnections have been changed to "connection points." Distributor C: Initial or central connection point in a hierarchical star topology. EQUIPMENT ROOM OR MAIN CROSS CONNECT Distributor B: Intermediate connection point between Distributor A and Distributor C in a hierarchical star topology. AN OPTIONAL SECOND PATCH IN EQUIPMENT OR TELECOM ROOM OR MEDIA CONVERTER AND/OR REPEATER Distributor A: Intermediate connection point between Distributor C and Equipment Outlet in a hierarchical star topology. HORIZONTAL CROSS CONNECT, e.g. TELECOM ROOM or ZONE MUTOA Equipment Outlet: Final connection point in a hierarchical star topology. WORK AREA OUTLET In a typical commercial building, Distributor C would be the main cross-connect, Distributor A would be the horizontal cross-connect, and Equipment Outlet would be the telecommunications outlet (TO. ) Distributor B is optional and not often used. Connecting these points are "cabling subsystems" defined as: Cabling Subsystem 2 or 3: Cabling between either Distributor A and Distributor C or Distributor B and Distributor C. BACKBONE Cabling Subsystem 2: Cabling between Distributor A and Distributor B. CROSS CONNECT Cabling Subsystem 1: Cabling between Distributor A and Equipment Outlet. HORIZONTAL In addition, some of the definintions have changed: Centralized cabling, Fiber optics with a direct connection from the equipment to user is defined as: A cabling configuration from Distributor C to a centralized cross-connect using pull through cables, an interconnect, or splice at Distributor A. Consolidation point: A connection facility within Cabling Subsystem 1 for interconnection of cables extending from building pathways to the equipment outlet. These drawings illustrate some of the options within the standard architecture. Below is the "traditional" view of TIA-568 architecture:  Distributor B is optional and can be used for a connection, e.g. fiber splices, or media converters:  In fact, no intermediate connections are required, e.g. centralized fiber:  
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