In iOS, there is a setting under Mail, contacts and calendar for increase quote level. There is an option to turn it off and on. What does increase quote level mean?
It indents the text, like in a quoted reply in your email.
I'm sure you've seen them, when someone responds and the original email has a > mark before each sentence, then it grows with each subsequent response >>, then >>> and so on. That way it designates the old email from the new.
To me means it will put a sold line down the left side of the email to indicate the previous (or quoted/replied to) content. So you don't get it confused when typing your reply.
Edit. I was typing my response as u types the above one in which you are correct.