Note 2 to entry: A precise border between "ultraviolet radiation" and "visible radiation" cannot be defined, because visual sensation at wavelengths shorter than 400 nm is noted for very bright sources.
Note 3 to entry: In some applications the ultraviolet spectrum has also been divided into "far," "vacuum," and "near" ultraviolet; however, the borders necessarily vary with the application (e.g. in meteorology, optical design, photochemistry, thermal physics).
Note 4 to entry: This entry was numbered 845-01-05 in IEC 60050-845:1987.
Note 5 to entry: This entry was numbered 17-1367, 17-1389 and 17-1388 in CIE S 017:2011.