This value reports how many seconds have elapsed since a specific VINES routing-table entry was last refreshed, with -1 used as a special marker meaning the age doesn't apply rather than an actual elapsed time. An admin cares because a route whose age never resets could mean the sending neighbor stopped issuing routing updates for it, pointing to a stale or dead path. For example, on a WAN interface running RTP Version 0 configured for delta-only updates, this legitimately reads -1 instead of a real age value.