I'm in the process of changing out all of our XLR cables to Starquad. I've heard that some people use colors to differentiate lengths. Is there a uniform system for this, or does everybody just come up with their own? Ie. blue cable 100 feet, red cable 50 feet, etc.

If there is a standard, I'm unaware of it. Coding cable length by color is an old trick, but I don't know that anyone has standardized it.

I haven't heard of a standard either and I code mine from a different perspective. Instead of color code by length, I use color code for keeping up with L and R or other differences. For example you'll likely have two cables the same length going to the same destination for L and R. It wouldn't be helpful if both are the same color, so I use for example bLue for Left and oRange for Right, both of the same length.

I suppose you could use the standard color code (brown = 1, red = 2, orange = 3 etc.) to indicate that a red cable, for example, is either 20 or 200 feet long. You ought to be able to tell which just by looking at it or you could put a second color band on near the connectors to tell how many zeros (red with black band = 2 feet, red with brown band 20 feet, red with red band i.e. no band 200 feet...).

Marco
On video cables to my mixer, I just used different colored tapes on each cable and use a sharpie to mark cable length on the piece of tape - works fine.