More from the 2016 article...

... Ad Hoc Standard

A friend of mine in the computer world used to joke that the great thing about standards is that there are so many from which to choose.

Although the United States has only one stereo FM broadcasting technology today, there was an earlier half-step, ad hoc standard.

With the emergence of FM broadcasting, many AM stations added an FM signal, if for no other reason than to save a place in broadcasting's future. The question of what to do with these new FMs arose quickly.

A sort of marketplace "AM-FM stereo" system standard for binaural broadcasting appeared, with one channel on the AM (left) and the other on the FM (right). ...

Yeah, I remember those days of AM left channel, FM right channel broadcasts.

My parents had a radio with the switch selection, "AM/FM stereo" for that purpose.