User blog comment:Bubby3/Why no Greatly Mahlo cardinal in our weakly compact OCF?/@comment-1605058-20180606171052/@comment-27513631-20180608205404

To add to this, I'm reasonably confident all occurrences of the weakly compact in the definition of the ocf can be replaced with a greatly Mahlo, but this ruins the analogy between \(\Pi_n+2\) reflection and \(\Pi^1_n\) indescribable cardinals, and hence is not used.