well as its change with time, must be considered relative to the stress imposed on the fiber during handling, cabling, and installation for a given set of environmental conditions. There are three basic scenarios that can lead to strength degradation and failure by inducing flaw growth: dynamic fatigue, static fatigues, and zero-stress aging. Telcordia GR-20, Generic Requirements for Optical Fiber and Optical Fiber Cable, contains reliability and quality criteria to protect optical fiber in all operating conditions. The criteria concentrate on conditions in an outside plant (OSP) environment. For the indoor plant, similar criteria are in Telcordia GR-409, Generic Requirements for Indoor Fiber Optic Cable. Cable types OFC: Optical fiber, conductive OFN: Optical fiber, nonconductive OFCG: Optical fiber, conductive, general use OFNG: Optical fiber, nonconductive, general use OFCP: Optical fiber, conductive, plenum OFNP: Optical fiber, nonconductive, plenum OFCR: Optical fiber, conductive, riser OFNR: Optical fiber, nonconductive, riser OPGW: Optical fiber composite overhead ground wire ADSS: All-dielectric self-supporting OSP: Fiber optic cable, outside plant MDU: Fiber optics cable, multiple dwelling unit Jacket material The jacket material is application-specific. The material determines the mechanical robustness, chemical and UV radiation resistance, and so on. Some common jacket materials are LSZH, polyvinyl chloride, polyethylene, polyurethane, polybutylene terephthalate, and polyamide. Fiber material There are two main types of material used for optical fibers: glass and plastic. They offer widely different characteristics and find uses in very different applications. Generally, plastic fiber is used for very short-range and consumer applications, whereas glass fiber is used for short/medium-range (multi-mode) and long-range (single-mode) telecommunications. Color coding Patch cords The buffer or jacket on patchcords is often color-coded to indicate the type of fiber used. The strain relief "boot" that protects the fiber from bending at a connector is color-coded to indicate the type of connection. Connectors with a plastic shell (such as SC connectors) typically use a color-coded shell. Standard color codings for jackets (or buffers) and boots (or connector shells) are shown below: Remark: It is also possible that a small part of a connector is additionally color-coded, e.g. the lever of an E-2000 connector or a frame of an adapter. This additional color coding indicates the correct port for a patchcord, if many patchcords are installed at one point. Multi-fiber cables Individual fibers in a multi-fiber cable are often distinguished from one another by color-coded jackets or buffers on each fiber. The identification scheme used by