User blog comment:P進大好きbot/New Googological Ruler/@comment-39541634-20190722124029/@comment-39541634-20190723033104

Until the UNOCF craze swept the wiki, people used either Deedlit's notation (from his "Ordinal Notations Part III") or a variant of his notation that doesn't allow Veblen functions in the construction of new ordinals.The latter version was often used because it concides with Madore's Psi, which was always our standard notation below ψ(Ω_w).

In both variants, ψ_I(0) is the first Omega fixed point.

BTW I've tried to analyze Rathjen's OCF as you explained it to me, and it looks like this notation is much much  stronger than Deedlit's variant. In particular, Rathjen's ψ_I(0) seems to go beyond anything Deedlit can represent without Mahlos (something like ψ_M(1) in his Mahlo notation).

Is that right?

(possibly not. My understanding of these levels is very hazy)