Kelvin is an absolute temperature unit, which is used in science.
The color temperature is in Kelvin of a light source, a monitor or an image corresponds to the temperature of a perfectly black object, that would glow at this temperature.
Daylight is defined with 6500 Kelvin, standardized light for commercial printers and prepress in Europe is considered as D50 standard light with a color temperature of 5000 Kelvin.
The word “degrees” is incidentally not used in conjunction with Kelvin. A temperature of 5000 Kelvin is not referred to as “5000 degrees Kelvin,” but only over 5000 Kelvin or “K 5000”.
The Kodak Approval proofing system was introduced in the 90s by Kodak in the market. With a Kodak Approval system outstandingly accurate halftone proofs and production Dummies could be produced.
Due to the high cost of consumables (market prices for Kodak Approval proofs are up to 100 Euro / A3 sheet) and the long processing time in the proofer and the elaborate laminating of the the proofs, Kodak Approval system are now only rarely found in the market. They were replaced by the faster, cheaper and in the color rendering significantly better and more accurate inkjet proofing systems.