Supplies the mantissa, or leading significant digit, of a Severely Errored Seconds threshold used by the BERT engine, paired with teraBERTSESThresholdExponent to form a scientific-notation value like N times 10 to the E. The DESCRIPTION is empty in this MIB, so this reading is inferred from the object name and standard telecom SES threshold conventions rather than vendor text. A mantissa of 3 combined with an appropriate exponent would set the SES threshold to 3 times 10 to that exponent errored seconds.