User blog comment:Hyp cos/Taranovsky has updated his ordinal notation page/@comment-29014792-20160910112131/@comment-5029411-20170228114527

sDDN confirmed.

(A)+ will be A-separator of {_+}.

My idea:
 * if ` and ,, are 1-separators and 2-separators
 * Then : and + are dropper-1-separators (dropper-expanding) and dropper-2-separators.
 * And (A)-2 represents dropper-A-separators instead of A-separators.