No C1, a lot of C2 errors - what that's means?

I’m using old Teac W512EB cd-burner and LiteOn 1653 dvd-burner. I have a lot of no-name CD-R discs. The disc surface looks like metal-AZO. Nero CD-speed and kprobe quality test results are strange – 0 C1, and average (!) 80 C2 errors, but there is no problem with reading of data. What that’s mean???

Teac W512EB is not in Nero CD-speed’s list of supported drives, but one may use some of such drives to scan for C2 errors, though C1 errors will not be reported. Whether the reported C2 errors are true is not known. I am not familiar with LiteOn 1653.

I’m using only LiteOn burner and both kprobe and CD-speed software to scan for errors. The results of testing of all other media are normal.