# DEFINITIONS OF TERMS USED IN THIS ANNEX

## "Time constant" (6) is the time taken from the application of a light stimulus for the current increment to reach a value of 1-1/e times the final value (i.e., 63 % of the final value).

**DEFINITIONS OF TERMS USED IN THIS ANNEX**

"Time constant" (6) is the time taken from the application of a light stimulus for the current increment to reach a value of 1-1/e times the final value (i.e., 63 % of the final value).

N.B.: Category references are given in brackets after the defined term.