Chicago basement ceiling height: 7'6" or 7'?

[Abby S.]

I have a non conforming basement unit in a legal 3 flat. The ceilings in the basement are a hair over 7' (full size door fits), and trying to understand whether to duplex down my first floor unit and go from 3/1 to 4/2 bed/bath legally. 

Per the link below, I'm seeing that in a "sleeping space" that the ceilings are permitted to be 7' (or less, for a bathroom):

https://www.map-strategies.com...

However, the chicago code says the height should be 7' 6":

https://chicagocode.org/13-64-....

So which is it?