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  <h3>lang (as an attribute name)</h3>
  <p>denotes an attribute whose value is a language code for the natural language of the content of any element; its value is inherited. This name is reserved by virtue of its definition in the XML specification.</p>
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  <h4>Notes</h4>
  <p>Attempting to install the relevant ISO 2- and 3-letter codes as the enumerated possible values is probably never going to be a realistic possibility.</p>
  <p>See BCP 47 at
    <a href="http://www.rfc-editor.org/rfc/bcp/bcp47.txt">http://www.rfc-editor.org/rfc/bcp/bcp47.txt</a>and the IANA language subtag registry at
    <a href="http://www.iana.org/assignments/language-subtag-registry">http://www.iana.org/assignments/language-subtag-registry</a>for further information.</p>
  <p>The union allows for the 'un-declaration' of xml:lang with the empty string.</p>
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