What are the keys solid aplle & blank apple for?

[wrxsti86]

Rescently ,I found the classic aplle II got two keys

one solid & one blank apple

What are they for? Would somebody well knowing to told me

a lot appreciation !

 

[stoid]

Shortcuts today that are listed as Apple-whatever used to be Open-Apple-whatever. I don't remember what the 'closed' Apple was for though.