Library /sys$common/syshlp/nclhelp.hlb set, routing, circuit, isis_hello_timer  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Support: L1,L2
    Default: 3             Value: 1-32767

    Interval, in seconds, between LAN level 1 and level 2 router-to-
    router Hello messages. This value is also used as the interval
    between IS Hello messages when polling the ES configuration.