This object configures the Unavailable Seconds (UAS) threshold for the current 15-minute interval on the SONET line layer, above which an alarm is generated, applying equally to Far End and Near End measurements. Because UAS specifically tracks seconds the line was unavailable rather than just error-prone, an administrator uses this threshold to catch outright outages within a short measurement window. For example, exceeding this threshold would mean the line was actually down or unusable for more seconds than the administrator considers acceptable within that 15-minute window.