User blog comment:Deedlit11/Ordinal Notations VI: Up to a weakly compact cardinal/@comment-30004975-20180116061613/@comment-5529393-20180130075945

Perhaps;  I'm not sure whether W, I fit in that well, but certainly M,K,... could probably be extended, and probably in more than one way. But, I like to use the term diagonalizer more specifically, like \(\Omega\) in the Bachmann-Howard notation, where each additional power of \(\Omega\) takes the fixed point operator of the previous function. Anyway, I'll describe more precisely what the indescribables do, rather than the rather vague statement of "diagonalize over W,I,M,K."