ESs. Errored Seconds encountered by a SONET/SDH section
SESs. Severely Errored Seconds encountered by a SONET/SDH section.
SEFSs. Severely Errored Framing Seconds encountered by a SONET/SDH section.
CVs. Coding Violations encountered by a SONET/SDH section
UASs. Unavailable Seconds encountered by a SONET/SDH section.