XML Schema for Sitemap index files. Last Modifed 2006-07-25 Container for a set of up to 1,000 sitemap URLs. This is the root element of the XML file. Container for the data needed to describe a sitemap. REQUIRED: The location URI of a sitemap. The URI must conform to RFC 2396 (http://www.ietf.org/rfc/rfc2396.txt). OPTIONAL: The date the sitemap was last modified. The date must conform to the W3C DATETIME format (http://www.w3.org/TR/NOTE-datetime). Example: 2005-05-10 Lastmod may also contain a timestamp. Example: 2005-05-10T17:33:30+08:00