I became aware of it some time ago when somebody at work was telling a story about attending a concert once when he had the bright idea of tying a balloon to the car so they could find it among the other 1,000's of cars in the car park afterwards. When he came out, there were dozens of balloons attached to cars in the car park
Our G.I.S mapping girl told us about it and shown us how to use it as a locating tool
