Quote Originally Posted by Tom1956 View Post
Perhaps put another way, black and white film tungsten ratings, or metering in other lighting conditions than daylight. I believe it is universally accepted that exposure meter sensitivity is planned to be in the 5600K neighborhood of color temperature. But what about metering in other lighting?
I don't know what current ISO standards call for, but going back to 1970s ANSI standards, the reference standard was 4700 K. (see the following)

From ANSI PH3.49 - 1971, Appendix B:

The primary standard for color temperature of a 4700 K radiation consists of a tungsten lamp operated at 2854 K in combination of the Davis and Gibson filter. This source not only matches closely the spectral-energy distribution of a blackbody at 4700 K, but is also reproducable from specifications.
All they had to say about spectral response requirements for the meter was that it had to be "continuous in the range between 350 nm and 700 nm." But the test seemed less complete, only requiring that the light detector match readings (at fixed luminances) at 2854 K vs 4700 K.