It's been a while, but my recollection is thus;
The Cisco parser ignores lines that start with !. So if you create a config on a computer somewhere for input to a router via TFTP or cut/paste, you can put in all the ! comments you want and they will have no effect on the configuration executed or saved on the router.
When in "Interface configuration mode" you can use the "description" subcommand to add a comment to the interface.
Now, what was your wireless question :^)
