Note 1 to entry: The defined datum axis can be any feature of the luminaire but it will usually relate to a feature that is nominally aligned with the horizontal such as an axis through the luminous opening or an axis through an array of LEDs or a fixing spigot entry axis.

Note 2 to entry: The tilt in application is the actual tilt of the luminaire when it is mounted for field use and should not be confused with "tilt normal in application" or "designed attitude" (see CIE 121, The Photometry and Goniophotometry of Luminaires).

Note 3 to entry: The tilt in application is expressed in radian (rad) or degree (°).