Default:HF, HCl, HBr, HI, HAt
Neutral atoms: 1 bond is allowed.
Two of the ligands should be F, Cl or oxygen; and one more atom from the 14th, 15th, 16th columns.
Double bonded oxygen and one any other atom from 14th, 15th, 16th columns are also accepted.
Four of the ligands should be F, Cl or oxygen; and one more atom from the 14th, 15th, 16th columns. Double bonded oxygens are accepted.
IF7 is accepted.
HXOy, where X = Cl, Br, I or At; and y = 2, 3 or 4.
F-, Cl-, Br-, I-, At- are accepted.
1+ charged ions: 2 filled valences are necessary (bonds or radicals). If absent, implicit Hydrogen atoms added.
1 Radical with 0 bond around the halogen atom is accepted.