title: TEI format vs. SGML format
body: <p>Can anybody explain the difference between <a href="http://en.wikipedia.org/wiki/Text_Encoding_Initiative" rel="nofollow">TEI</a> and <a href="http://en.wikipedia.org/wiki/Standard_Generalized_Markup_Language" rel="nofollow">SGML</a> format and/or how they are related?</p>