What is the format of Netscape's Bookmarks for URLs?

By the time Netscape assumed stewardship, the Open Directory Project had about 100,000 URLs indexed with contributions from about 4500 editors. On October 5, 1999, the number of URLs indexed by ODP reached one million. According to an unofficial estimate, the number of URLs in the Open Directory surpassed the number of URLs in the Yahoo! Directory in April 2000 with about 1.6 million URLs. ODP achieved the milestones of indexing two million URLs on August 14, 2000, three million listings on November 18, 2001 and four million on December 3, 2003.