Forum signature and membership level

[Kyle McCorkel]

Can someone outline what I can put in my forum signature at different membership levels?

For example, I'm currently a "Pro", and I have my website in my signature.  Can I still put my website in my signature if I downgrade to "Plus" for "Free"?

Do I have other options if I were able to upgrade to Premium?

I can't find these answers anywhere.  Thanks in advance for the help.