I kinda think this was possibly discussed a very long time ago... I don't remember very well, but I *think* only the HH had a recessed enough centre to label? I could be totally wrong though. I'll see if I can find the threads I'm thinking about.
FWIW, I really like the circle square mold. It isn't as popular as some of the others, I know, but I really like it's simplicity.
Edited to add:
I found
this thread which discusses labelling various ASMs, see post 6 with a link to some circle-squares. Also see
another ASM labelling thread . Seems like at least one person has labelled CS but people don't recommend it?