...unless, mind, it's an NS marking. Could go either way, and that will complicate searching, I should think.
Interesting that in the advertisement you linked the phono is playing the famous aria from Mignon (in English, "Knowest Thou the Land?"), not some pop ditty. I doubt anyone would take that approach advertising a playback device today! Also, it illustrates how operas come and go from the standard repertoire; back then, Mignon was so familiar it could figure in such an advertisement as instantly recognizable, but today I doubt one could say the same, even if someone were inclined to refer to opera in that way.