Advance XHTML Programming Question:

URI (Uniform Resource Identifier) is a superset of URL. URI provides a simple and extensible means for identifying a resource in a more generic way. For example, the following strings are all valid URIs:

ftp://ftp.is.co.za/rfc/rfc1808.txt
http://www.ietf.org/rfc/rfc2396.txt
ldap://[2001:db8::7]/c=GB?objectClass?one
mailto:John.Doe@example.com
news:comp.infosystems.www.servers.unix
tel:+1-816-555-1212
telnet://192.0.2.16:80/
urn:oasis:names:specification:docbook:dtd:xml:4.1.2

When an XHTML document is published on the Internet, its location can be represented by a URL, which is also a URI.