Per its DESCRIPTION, this Counter64 counts seconds during which the Section layer lost frame alignment (the A1/A2 framing pattern could not be found), a Severely Errored Framing condition. Because this is a lifetime counter that only resets on an explicit clear, a reading here means the receiver briefly lost SONET frame lock and had to resynchronize on this OC-n (SONET) port, accumulated over the port's entire service life, not merely since the last reboot. For example, 5 seconds of severely errored framing lines up with a brief loss of clock reference rather than ordinary bit-level noise.