Jmol 14.32.49
4aoj AU has 6,412 total, 170 HETERO, 83 HOH, 0 hydrogen, 0 phosphorus, 721 *.cb.
4X 170=680, 721=2884, BM1 ALL 25,648

GETS 348 HETERO (√, w/o water), 0 HOH, 0 CB.
load MODELS ({0}) https://files.rcsb.org/download/4AOJ.pdb filter "!_H;*.CA,*.P,%A|HETATM,![HOH];biomolecule 1;bmchains"; 

14.32.57:

GETS NONE.
load MODELS ({0}) =4aoj filter "!_H;*.CA,*.P,![HOH];biomolecule 1;bmchains"; 

GETS 3120 CA == all, 0 hetero.
load MODELS ({0}) =4aoj filter "!_H;*.CA;biomolecule 1;bmchains"

GETS NONE. I think because the !_H converts "," to AND, so no atoms are CA and P.
load MODELS ({0}) =4aoj filter "!_H;*.CA,*.P;biomolecule 1;bmchains"
DITTO with !_H; -> !_H,
BUT !_H is UNNECESSARY since I'm taking only CA or P.

3HYD All = 544 including N hydrogens.
THIS WORKS getting total 268 atoms, 0 H.
load =3hyd filter "!_H;biomolecule 1;bmchains"
BUT N.B. !_H, fails, getting all.

THIS WORKS getting 32 *.ca == all. Note semicolons!!!
load =3hyd filter "!_H;*.ca;biomolecule 1;bmchains"

THIS FAILS NONE:
 load =3hyd filter "!_H;*.ca,*.p;biomolecule 1;bmchains"
 
THIS WORKS 32 ca only == total. NOTE SEMICOLONS:
 load =3hyd filter "!_H;*.ca;*.p;biomolecule 1;bmchains"
AND IT WORKS WITH NUCLEIC:
load =1FLO filter "!_H;*.ca;*.p;biomolecule 1;bmchains"

TESTS in 14.32.58 with new "ALLHET" feature ("HETATM" still doesn't work)
load =1FLO filter "!_H;*.ca;*.p;%A;allhet;biomolecule 1;bmchains"
YES gets bbonly plus 16 non-water hetero atoms.


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Testing for *.ca with altlocs.
1zir has 5 *.ca each with 2 altlocs, seq 1115-1119.
load =1zir # 1,771 atoms.

load =1zir filter "*.ca" # 178 atoms, expect 173 for config 1.

load =1zir filter "*.ca,%A" # NONE

load =1zir filter "*.ca;%A" # 173! note SEMICOLON

THIS WORKS GETTING 173 CAO, 0 hetero:
load =1zir filter "!_H;*.ca;*.p;%A;biomolecule 1;bmchains"