163 describes criteria for the installation of optical fibre cables defined in Recommendation ITU-T L. Distributed fiber optic sensing. Distributed fiber optic sensing techniques, such as DAS, DSS or DTS are powerful tools for the monitoring of long, linear assets. FO-VC2 JOINT USE - VERICAL MIDSPAN CLEARANCES 48. (FOA) was founded in 1995 to help develop the workforce to build the fiber optic networks to support a rapid expansion in communications and the Internet.