Cell Transfer Delay (CTD):     mean CTD < N ms 
 Cell Delay Variation (CDV):     difference between 
 upper and lower 10–8 quantiles of CTD < N ms
 Cell Loss Ratio (CLR):     
 < N x 10-7
 (less often
 specified)
 Cell Error Ratio (CER):     
 < N x 10-6
 Cell Misinsertion Rate (CMR):     
 < N / day
 Severely Errored Cell Block Ratio (SECBR): < N x 10-4