This procedure is used to determine the ratio in decibels of the power reflected by the port of a component or assembly to the incident power on the same port of that component or assembly when that component or assembly is introduced into a link or system. The ratio is termed " Return Loss" when applied to a fiber optic system or link. Return loss, by convention, is a positive number. The ratio of relfected to incident power is termed " Reflectance" when applied to an individual component. Reflectance, by convention, is a negative number.