This object indicates the string-value identifying the UNI
that is in the EVC. For UNI that is local, this value is the
same as cevcUniIdentifier for the same ifIndex value as
cevcEvcLocalUniIfIndex. For UNI that is not on the system,
this value may be derived from the underlying OAM protocol.
If the UNI identifier value is not specified for the UNI or it
is unknown, the value of the cevcEvcUniId column is a
zero-length string.