FIBER OPTIC PATCH CORD Apsys Networks fiber optic patch cables are ideal for supporting high speed telecommunication network fiber applications.They are manufactured and tested in compliance with TIA 604 (FOCIS), IEC 61754 and YD/T industry standards.In fiber optic systems, multimode fiber is optical fiber that is designed to carrymultiple light rays or modes concurrently, each at a slightly different reflection angle within the optical fiber core.