Lightcode - Universal Light Code (ULC) is an open membership, public read access (anyone can view files), only members can post (including photos), mailing list. This is a forum for those interested in a discussion of light as it relates to the Universal Light Code (ULC), a system for accounting for the quantity of light in a scene. The decoder for the ULC is available at the Black Cat Photo site (see Related Link below), as a freeware nomograph chart called the Black Cat Exposure Tetrad or as a commercial dial-type version called the Black Cat Extended Range Exposure Guide.