Blank dvd disc question

I’ve noticed a lot of dvds have little…I don’t know what you would call them…ridges/bumps on the sides of the disc. Not on either flat part, but on the outer edges of them. Is this normal? Does anyone even know what the hell I am talking about?

My Taiyo Yuden’s have them and they burn sweetly, so I guess that the bumps are nothing to be concerned about.

I think its just excess glue that has squeezed out during the disc manufacturing process. Nothing to worry about as far as I know.