This read-only integer reports how many of the possible 96 fifteen-minute history intervals actually contain valid collected data, which will be less than 96 only if the link interface has been online for under 24 hours. A manager checks this before trusting the full 24-hour history table, since a low count means the terminal simply hasn't been up long enough to fill it yet. For example, seeing wvLinkValidIntervals report 20 shortly after a terminal reboot confirms only 5 hours of interval history exists so far, and the rest of the 96-slot table shouldn't be treated as meaningful.