This attribute specifies the OSPF tag to be used on the routes being
exported as a result of matching this export policy.
If the attribute advertiseStatus is set to block, then the value of tag is
ignored. The tag value is not used to select which routes to block or
send, but rather the tag value advertised for the routes.
A value of 4294967295 indicates that the tag associated with the route in
the forwarding table is used.