I am novice in the business of typography so you have to pardon the ignorance in my question, but it goes like this:
What happened to Standard Medium, the typeface used in the New York City Subway Transit?

I am cannot find it in any library of typeface. It is not a widespread type. I cannot find a digital version. I am troubled by this. I want to know where I can find it. The graphics were commissionned to Unimark, and done by Bob Noorda in Milan, the Graphics standards manual was done by Massimo Vignelli in New York.