[kaptain]

Curious as to why the markings on the new push pull state "not a parking brake" ?

I think it's just the default knob that comes with the pull-push valve. 
You use it with another knob like this one,   https://www.finditparts.com/g/bendix-298818-3504455
then it becomes a parking brake.

And I think Newell probably uses "Emergency Brake" and "Parking Brake" interchangeably because on my coach 701, the yellow Bendix knob is marked as "Parking Brake," and it controls the status of the LED light on the panel in front of the driver seat marked as "EMERG BRAKE."