View IES Light
IES Lights are a specific type of light that uses actual light energy and pattern descriptions from manufacturers of actual light systems. For many years now, lighting manufacturers have been publishing their product characteristics using the IES specification, and Cinema 4D takes advantage of that. Why should you bother? Well, architects will often specify the lighting they wish to use in the spaces they are designing, and do so with IES specs. In fact, if you were to build a set and light it to match its real world counterpart, you will notice very little variation (at least in the ligthing).
IES specs define the perfect light, and the does not specify color temperature. Instead, the IES specs have distribution patterns and energy output only. However, you do have the freedom to set your colors, and to work within the range specified to that particular lighting option, so you do have some creative contribution to make. In addition, since IES lights are perfect, actually too perfect, you may want to fudge with them a bit to add a more human touch.