This attribute indicates the total number of one second intervals for
which the STS line is unavailable. The STS line becomes
unavailable at the onset of 10 consecutive LSESs. The 10 LSESs are
included in the unavailable time. Once unavailable, the STS line
becomes available at the onset of 10 contiguous seconds with no
LSES. The 10 seconds with no LSES are excluded from the
unavailable time. For second intervals where a Line Unavailable
Second (LUAS) is counted, counting of LCV, LES, LSES and
LAISS is inhibited.