rsync command

[Robert Holtzman]

I shamelessly cribbed the following command off of a previous post:

rsync -vaHz --exclude '/proc' --exclude '/sys' --exclude '/media' /. 
/media/disk

What I'm hazy on is the significance of "/." prior to "/media/disk". 
There is a murky reference in the man page to merge in reference to "." 
but I'm not sure it applies here.

I know I'll be embarrassed to find out how simple/obvious the answer is 
but it just isn't coming thru to me.

-- 
Bob Holtzman
"If you think you're getting free lunch,
  check the price of the beer"