Also, Google, Yahoo, MSN announced auto-discovery for sitemaps through codice 1. Many sites have user-visible sitemaps which present a systematic view, typically hierarchical, of the site. The standard can be used in conjunction with Sitemaps, a robot inclusion standard for websites. In April 2007, Ask.com and IBM announced support for Sitemaps. Since 2009, Yandex has supported Sitemaps technology. Sitemaps may be addressed to users or to software. Bing, Google, Yahoo and Ask now jointly support the Sitemaps protocol. Sitemaps can be compressed using gzip, reducing bandwidth consumption. Sitemaps can also be just a plain text list of URLs. Google's Sitemaps protocol and mod oai are intended to allow discovery of these deep-Web resources. Sitemaps allow the user to determine how the devices in the smart home are arranged.