hi
I did spend 10 minutes to try to use that, I will say it cautiously to avoid to hurt some one, "difficult" as well as "surprising" commands! Nothing to do any more (I know I did use them years ago...):
Allowed markup: a blockquote code em strong ul ol li img.
Put code in between backticks
.
rgds
http://www.w3schools.com/tags/tag_blockquote.asp
http://help.squarespace.com/customer/portal/articles/537151-using-the-quote-block