Fans of my fiction writing will doubtless remember my theory that in the Future, girls' school-uniform skirts will be made of "smart fiber," capable of changing colour under computer control to act as a sort of display screen, and the wearers will use that to encode personal information into the plaid stripes of something like a present-day 2D barcode. Such technology already exists today (it's closely related to "e-paper"), though it isn't cheap and rugged enough yet for serious use in clothing.
Well, in one of my nefarious projects I recently had occasion to actually use a data-to-tartan encoding scheme, and you might find the results interesting. Here's a sample:
See if you can reverse-engineer the encoding that generated those swatches. It's quite simple, and has an historical basis.