About grade of a media



There is now 6 month I take more care about media which I use.

I'm curious and I would like to know exactly how media quality is check ?
What are the criteria, the standarts to define the grade of the media ?
What means exactly grade A, B, C ? Value about error/ defect tolerance for each grade.



A/B/C Grades have nothing to do with actual media quality ; if you care about
burning quality nothing can replace your own tests (CDspeed, Kprobe, etc).

The meaning of A/B/C and +/- is explained in this thread :