Default choice of hydrogen placing in dihydrobenzothiopyran-3-thione

[IngvarLa]

This might be a bit esoteric but, and admittedly the names are incomplete.
benzothiopyran is by default 2H-benzothiopyran
In dihydrobenzothiopyran, the default choice is 3,4-dihydro-2H-benzothiopyran
In dihydrobenzothiopyran-3-thione, the default choice is 4a,5-dihydro which looks odd, any reason why not 3,4-dihydro here.
O1CC(CC2C1=CC=CC2)=O not O1CC(CC2=C1C=CC=C2)=O

Similarly for dihydrobenzopyran-3-one, dihydrobenzoselenopyran-3-selenone etc