This reports, in seconds, how much of the current 15-minute far-end error-measurement window has elapsed so far, counting up toward the full 900-second period. An admin needs this to correctly interpret a partial far-end counter mid-interval -- a far-end errored-seconds count of 30 means something very different if this reads 60 seconds (a very bad start) versus 890 seconds (a fairly clean, nearly-complete quarter-hour). If this reads 450, the current bucket is exactly half-finished, so any far-end counts observed so far should be roughly doubled to estimate the likely full-interval total.