Each endpoint a completed backfill paged; blocks null when it was empty.
ISO 8601.
Every endpoint of the network's family is covered.
The network's endpoints no completed backfill paged, in paging order.
The network's display name.
The latest backfill run, ISO 8601 dates: running, or how it closed without
completing. null when none ran or the last one completed.
One address on one network, and what its history backfills covered.