Could coloured sails identify fleets in battle?

Were coloured sails used to identify ships during large fleet battles?

Large stern flags were the main means of identification. Neither hull paint nor sail colour supplied a dependable uniform fleet scheme.

Large flags flown at the stern were the principal means of identifying friend or foe. Ships in one fleet did not share a uniform paint scheme, and some could resemble enemy ships more closely than their own companions. Painting sails for identification was possible, but the colour would not necessarily remain useful throughout a prolonged campaign. Nelson's ships before Trafalgar provide the example of vessels that had already spent a long time at sea.