YES tells the client when it finds a redirected URL to return the destination URL as well. NO, the results sent to the Server will not give any hint whether there was a redirect or not. URLS-DUE are the URLs which the Server has directed the Client to crawl, and the results after the crawling. With-contents have a new content to report to the Server because either a brand new to the Server URL was crawled, or an existing URL has updated its content. This protocol assumes that the Server indexes URLs using their CRC-64 value.
Plain hits are all of the other words in the doc.
This hit type may be dropped altogether if the Server requires that.