I'm trying to understand an Aflat-7 run that starts over a D-7 and continues over a G7 (Measure 61-62). The comment under these measures states, "thinking Aflat-7 which is the II for the tritone sub of G7".
I'm trying to understand what II means in this context. I understand that Dflat is the tritone of G. The II of Dflat is Eflat (not Aflat).