What does it mean to set a terminal's "icon title"?

I generally see the syntax for setting the terminal title as (something like): echo -e '\e]0;Some Title\a' But I noticed this answer used 2 instead of 0, which prompted me to do a little more digging. According to this document you can actually set both the "icon name" and the "window title" with this syntax: > · ESC]0;stringBEL -- Set icon name and window title to string > > · ESC]1;stringBEL -- Set icon name to string > > · ESC]2;stringBEL -- Set window title to string > > where ESC is the escape character (\033), and BEL is the bell > character (\007). > > Printing one of these sequences within the xterm will cause the window > or icon title to be changed. But it doesn't go on to explain what exactly it means by "icon title" or "icon name". When I try it out I don't see any difference between 0 and 2, and 1 doesn't *appear* to do anything. So what is the "icon title", and what is supposed to happen when 0 or 1 is called?