michaels, hobby lobby, and plenty of other places sell enamel paint pens (fine and medium points), in various colors for coding: e.g., two dozen 20'+ cables get red numbers (1-24), ten 15' cables get green numbers (1-10), twelve 10' cables get yellow numbers (1-12), etc, yada yada. now they are not only color coded, but as they have numbers: easy to track down issues at the stage box (or mixer) on both ends! easy to identify in the box/trunk. easy to do, quickly, and other identifiers can be added (e.g., dmx...)
multi-colored paint pens: can be reused until the paint runs out!
multi-colored paint pens: can be reused until the paint runs out!