What does "list-alt-remaining" mean?

My question to that is - as it sometimes seems to be a topic in Omnifocus but also in Omnioutliner:
what does “alt” in the context (or shall I say perspective) “list-alt-remaining” mean?
Sorry, I just couldn’t find it. I see that the difference between “alt” or “no alt” is that the bullet points are either on the left side (alt) or on the right side (no alt) of the list (icon).
Can anybody enlighten me here?
Thanks a lot,

This seems to be referring to my perspective icon set?

If so, then yeah, the ‘alt’ just refers to the checkboxes being on the left instead of the right.