n></dt><dd><code>url</code> - url of the page</dd><dd><code>doc</code> - Lucene document. NOTE: this already contains all information collected
 by indexing filters. Implementations may modify this instance, in order to store/remove
 some information.</dd><dd><code>dbDatum</code> - current page from CrawlDb. NOTE: changes made to this instance
 are not persisted.</dd><dd><code>fetchDatum</code> - datum from FetcherOutput (containing among others the fetching status)</dd><dd><code>parse</code> - parsing resu