That is one of those things I found would never do anything by changing it.
IIRC its 49 degrees as a default value on both t4m0 and j4j1
I once set it at 21 with my tip in retard at 36 which was same as max
value in my base spark table. When I tipped in the throttle, I saw 36.
That at least tells me it does not effect or over ride my tip in scalar.
I looked it up a good while back in some help notes I got from SCT
which seemed to be describing it as working with knock sensors ...
which we don't have. Most likely ... They were talking about a pcm
of later date than ours.