You wrote in the "A Digital Imaging Revolution in The Making"
It's worth noting that if you find yourself shooting under very weird lighting conditions, such as unknown fluorescents and mixed conditions, all that one needs to do is take out a ColorChecker (even the little pocket version) and take a shot of it under the unusual lighting.
Working with the color checker tab each time the light is a problem is quiet fascinating, but it doesn't work apparently. Under 4800 K, I have an error message: " Please reshoot the cast carefully to avoid color casts and try again."
And if I read the DNG editor tutorial:
Photograph the ColorChecker Chart under a 6500 K illuminant (e.g., D65 simulator), taking care to illuminant the chart evenly and to minimize color casts.
You have to take the photograph under a 6500 K illuminant.