This is the minimum interval, in seconds, between sending Partial Sequence Number PDUs at this level, following the resettingTimer behavior. PSNPs are used both to acknowledge received LSPs on point-to-point circuits and to explicitly request specific missing LSPs after a CSNP reveals a gap, so this throttle prevents the router from bursting out PSNPs faster than this interval even if many acknowledgments or requests become necessary at once. For example, after a large-scale topology change forces this router to request dozens of missing LSPs at once, this interval spaces out those PSNP requests instead of firing them all in a single burst.