External References
[ISO639] http://www.infoterm.info/standardization/iso_639_1_2002.php
, http://www.loc.gov/standards/iso639-2/
(contains also ISO 639-1 language codes).
[ISO8601] http://www.iso.org/iso/catalogue_detail?csnumber=40874
, http://en.wikipedia.org/wiki/ISO_8601
.
[RFC1945] http://tools.ietf.org/html/rfc1945
.
[RFC2104] http://tools.ietf.org/html/rfc2104
.
[RFC4648] http://tools.ietf.org/html/rfc4648
.
[RFC5545] http://tools.ietf.org/html/rfc5545
.