Google-maps – Google Maps Earth mode URL parameters

I have some questions about some of the parameters. Here's an example of the Statue of Liberty
https://www.google.com/maps/@40.6857974,-74.0453996,237a,20y,12.19h,59.76t/data=!3m1!1e3

@40.6857974,-74.0453996 is eye latitude,longitude in degrees decimal
237a is eye altitude in meters
20y is unknown
12.19h is heading in degrees decimal
59.76t is tilt in degrees decimal
data=!3m1!1e3 is unknown

Anyone able to figure out the meaning of the 2 unknowns? y in Streetview is the field of view, I'm guessing it's the same with Earth mode, but Google doesn't want people altering the FOV value which would explain why it's always reverting to 20y if you try to change it.

EDIT: yes, the y value is indeed FOV, looks like half of the horizontal FOV specifically. I noticed that when you zoom in first it widens the FOV (y value gets bigger) then as you zoom in more it goes into Streetview. Problem is if you copy a url with a y value other than 20 it'll simply change it back to 20.