Fascinating! Just as an aside, a lot of this kind of signaling goes on in flamenco dance troupes. I found this out when I was taking some flamenco guitar lessons in 1962. Some of the figures on the guitar are signals to the dancers, and some heel stomps are signals to the guitarist. One of them is three sharp, staccato chords on the guitar. This is the guitarist saying, "my fingers are about to fall off, so wrap it up!" The equivalent message is three sharp heel-stomps and a momentary pause, which is the dancer saying, "wrap it up, my feet are killin' me!"

Don Firth