I've been reading Samuel Eliot Morrison's outstanding series on the History of US Naval Operations in WW II. In the volume concerning the Guadalcanal campaign is this quote about one of the night actions:
"(Admiral) Scott, still not satisfied, wanted to know if his crusiers had been shooting at Tobin's destroyers. The squadron commander replied, "I don't know who you were firing at." Still uncertain, Scott ordered Tobin's three ships to flash their battle recognition lights. Lights green over green over white in a vertical position flickered momentarily to starboard."
HOWEVER, I believe that this pattern was NOT permanent, and I am not sure if green and white were the only colors used.
I suspect that like any other "challenge and reply/password" the pattern was changed to prevent the enemy from simply copying a known arrangement.
But certainly you can use this arrangement and know that at SOMETIME this particular pattern was used.
Tom