A sitemap directs search engines to the pages of interest in a web site so that the search engines can intelligently crawl your site. In the case of Evergreen, the primary pages of interest are the bibliographic record detail pages.
The sitemap generator script creates sitemaps that adhere to the http://sitemaps.org specification, including:
* limiting the number of URLs per sitemap file to no more than 50,000 URLs;
* providing the date that the bibliographic record was last edited, so that once a search engine has crawled all of your sites' record detail pages, it only has to reindex those pages that are new or have changed since the last crawl;
* generating a sitemap index file that points to each of the sitemap files. (2.7)