For all the discussion of what to be encoded how in that row, has anyone found a certain solution to the 'line above the grid'?
I understand how applying H to the title makes it thematically relevant to 'confirm' what we're doing with 'A'. But how to represent that in practice? A 'line' could be a pen stroke to alter the title (rather unsatisfactorily) as it stands, or a line of text with a revised version of the title. Those being possible but not definitive, there must surely be a penny-drop certainty that I'm not seeing.
I am increasingly feeling that there's something very devious about the use of D, H, and A, and that their meaning is not consistent from one part of the preamble to the next.