6.2 has a list of groups of elements which the reader
is invited to use when interpreting content models.

for 'points' (change-char-begin| end) I can see this as worthwhile.
  It is very specific.

I find it odd that the out of line items aren't simply added to the content lists in section 6. They are so few it wouldn't be much work.
I refer to float and footnote.

The first block of 'neutral' containers,      
     multi-switch
     multi-properties
     index-range-begin
     index-range-end
     wrapper
     retrieve-marker

could be integrated with a key inversion?

e.g.
%block; replaced by current block definition , multi-switch .. retrieve-marker +
  float
%inline; replaced by current inlines + multi-switch..retrieve-marker + float
   + footnote
%PCDATA; repalced by multi-switch .. retrieve-marker + float + footnote

The general provision about "provided that the additional constraints listed under each formatting object are satisfied,"  would then become an override.