source of the most recent subscription order from an individual subscriber. Subscription records renewed at least once usually contain information about the original source (see original order), the prior source, and the latest source, so that source-to source migration can be tracked. This helps the publisher discover how best to promote the renewal of subscriptions sold via different sources. For example, an agent-sold subscription renewed for the first time through the publisher’s own renewal promotion has an agency original source and prior source, and a renewal latest source. If this subscriber renews again with an insert card, the prior source is a renewal and the latest source is an insert card. The original source (agency) does not change.