Triac quadrants

[Exo]

I'm making something similar to the circuit in this app note
https://www.electro-tech-online.com/custompdfs/2004/10/40171a-2.pdf
(scematic on page 10 - the pic's output is high to fire the triac and Hi-Z for no fire)

I need to know in wich quadrants the triac operates when it is setup this way. I figure it's in quadrants 1 and 4, can someone verify this?

 

[williB]

if i recall it seems to be firing in th second and fourth Quadrant..
right before the sine wave crosses zero.. as it should..