On the face of it, Rule 1a sounds simple enough to implement. And it is, except for the special cases discussed in BB 2013 P-92.1.4.4 in relation to compounds and ions with multiple chemically equivalent Kekulé structures, such as benzene, pyridine or cyclopentadienyl anion. That section briefly introduces the idea of "atomic number averaging" for mancude-ring systems, which are "rings having (formally) the maximum number of noncumulative double bonds, e.g. benzene, indene, indole, 4H-1,3-dioxine". The idea is to average the atomic number of the duplicate node when it is involved in multiple resonance structures. Our reading of Section P-92.1.4.4 is that it is not a wellcrafted guideline, with many unanswered questions. What exactly defines the pertinent cases for which this rule applies? What about acyclic cases such as allyl anion or acetoacetate? How exactly is the averaging to be done -Do we need to know the exact weighting of all the possible resonance structures, or is it sufficient to average over just the adjacent atoms involved in the electron delocalization?