The Universal Light Code (ULC) is copyrighted and trademarked. The light code is for personal use only. It may be used for commercial applications only with the written permission of the author.

The dial on the Black Cat Extended Range Exposure Guide is based on a new light code that forms a notation for natural, existing, and available light, spanning the full range of human vision: fresh snow in sunlight, CODE A to grass in starlight CODE Z.

There are currently only arbitrary scales or codes for reflected light in use by photographers. There is no universal or international standard used as a primary benchmark for photographers. The Black Cat Guide establishes the UNIVERSAL LIGHT CODE (ULC). A simple code for photographic notation consisting of twenty six "file folders" that contain the full range of light that can be seen by the human eye. The exposure dial acts as a "decoder" and translates the scene into exposure settings. For example: a full moon (man-in-the-moon) is CODE C and lightning is CODE K. Anyone armed with the UNIVERSAL LIGHT CODE for a scene has the knowledge that currently belongs to the professional.