What/where is this "AS-1" window tint line on our old windshields?

[j-c-c-62]

Do replacement windshields have it?
I am not a fan of "green" tint windshields, so on a clear windshield, I'm curious where this "AS-1 line" is if marked, so I can tint the top part myself.

 

[69L48Z27]

Never noticed it on these 60’s and early 70’s cars. Might be something that started showing up in the 80’s?

 

[Runcharger]

The band is about 4 inches wide and fades the lower it goes.

 

[j-c-c-62]

Florida Statue 316.2952 
(b) Sunscreening material along a strip at the top of the windshield, so long as such material is transparent and does not encroach upon the driver’s direct forward viewing area as more particularly described and defined in Federal Motor Vehicle Safety Standards No. 205 as the AS/1 portion of the windshield.

 

[RemCharger]

This one has an original windshield and appears about 3.5" ( from the gasket edge) and the other car is the same but not a factory window.

 

[j-c-c-62]

What year is that original AS1 marked windshield?
Seems like this marking might have started in 1968?

 

[RemCharger]

It's from a 66-7 B ( Charger)