This read-only value is the source IPv6 address found in an ICMPv6 error reply received in response to the ping6 test, such as from an intermediate router reporting an error. An admin uses this to identify which hop along the path generated an error, such as a hop-limit-exceeded or destination-unreachable message, when the ping doesn't simply succeed or time out. For example, this object reporting the address of an intermediate router rather than the ping target itself would tell the admin the packet was rejected partway along the path, not by the destination.