The color rendering properties of the light source cannot be assessed by visual inspection of the lamps alone. In order to provide a color rendering index that will in all cases represent the facts, it is necessary to have accurate and precise spectroradiaometric measurements of light sources and an adequate understanding of color vision. Neither is routinely available so that today no complete answer to the problem can be provided. Some countries have recommended a minimum color rendering index of 50 for apron floodlighting, but this value may be a result of accommodation rather than scientific determination. In the final analysis, the limitation of light sources remains a matter of experience and subjective knowledge of the color rendering capabilities of the sources which are available on the market today.