Albums which are over 18 months old (from the date of release) and have dropped below position 100 on The Billboard 200 were removed from that chart and placed on the Top Pop Catalog Albums chart.
Until November 2007, albums sold as an "exclusive" to a particular retail outlet (such as iTunes, Starbucks, or Wal-Mart) were not eligible for the Billboard 200 due to a long-standing policy.
This policy was changed following the first-week success of The Eagles' album Long Road Out of Eden, sold exclusively at Wal-Mart and on the Eagles' website; the rule change took effect with the issue dated November 17, 2007.
Instead, it could be viewed via paid subscription to Billboard's online service, Billboard.biz.
Three of Michael Jackson's albums (Number Ones, The Essential Michael Jackson and Thriller) claimed positions 1-3 respectively on Top Pop Catalog Albums and Top Comprehensive Albums in the week following Jackson's death.