Jambo
In those days it was the GS mode of a quaint form of kit called a Van X DME, forerunner to the current Int DME. DME an Oz invention by AWA in the good old days, when men were men, drank beer instead of chardonnay, leapt tall buildings with VLF Omega gear and wimmen did the washing up and ironed blokes shirts
BTW if Superman is so smart how come he wears his underpants outside his tights.