I'm referring to https://processwire.com/api/selectors/ under the section, "Subfield selectors". It says, "
"If you instead want to find all pages that have at least one building greater than 1000 feet that also happens to be built before 1980 (matching the same exact building, even if the page has multiple buildings) then you can specify that in the selector by preceding the field name with a "@", i.e."
I was slightly wrong in describing the way it is functioning.
R.a.count doesn't matter, so I've removed it from the string and tried both, "@R.b.count=0, @R.c.count=0" and, "R.b.count=0, R.c.count=0"
Both return the same results, pages that have either R.b.count=0 OR R.c.count=0, or both=0.
What I need is pages that R.b.count=0 and R.c.count=0 where both R's are the exact same R. In other words, pages that have an R where b.count=0 AND c.count=0.