>Is this the "square cloth handkerchief (white w/ black)?"
No, it is not. Is is square? No. Go look for the paintings done by an artist who was victimized as a child, look at the handkerchiefs in those paintings. Although there might be something nefarious about the use of these tops these girls are wearing, clothing with this paisley pattern comes and goes in style, it was big with hippies, so it would be pointless to use it as some kind of signal, the pattern is plugged into the mainstream.