Her 'rule of thumb' (pun intended) is that a mini skirt's hem should not be any shorter than a wearer's thumb when the hands are at the side. I actually think, however, that you have to see the wearer and the garment and that rules like that don't always apply across the board. Plus, the thumb line can be pretty short.
Ancient historians from both China and Rome noted the use of white flags to signal surrender. In the former empire, the tradition is believed to have originated with the reign of the Eastern Han dynasty (A.D 25-220), though it may be somewhat older. The Roman writer Cornelius Tacitus mentions a white flag of surrender in his Histories, first published in A.D. 109.
Some solo flags mean specific things. For instance Code Flag B means they are protesting another boat in the race. It can also mean you are loading fuel or explosives. Code Flag Q is an quarantine flag, or the boat is quarantined. Code Flag L means come with in hailing distance.