The value of this attribute is always understood to be a single token, even if it contains space or other punctuation characters, and need not be composed of numbers only. It is typically used to specify the numbering of chapters, sections, list items, etc.; it may also be used in the specification of a standard reference system for the text.
<p> … The consequences of this rapid depopulation were the loss of the last <foreign xml:lang="rap">ariki</foreign> or chief (Routledge 1920:205,210) and their connections to ancestral territorial organization.</p>
The xml:lang value will be inherited from the immediately enclosing element, or from its parent, and so on up the document hierarchy. It is generally good practice to specify xml:lang at the highest appropriate level, noticing that a different default may be needed for the teiHeader from that needed for the associated resource element or elements, and that a single TEI document may contain texts in many languages.
Only attributes with free text values (rare in these guidelines) will be in the scope of xml:lang.
The value used must conform with BCP 47. If the value is a private use code (i.e., starts with x- or contains -x-), a language element with a matching value for its ident attribute should be supplied in the TEI header to document this value. Such documentation may also optionally be supplied for non-private-use codes, though these must remain consistent with their (IETF)Internet Engineering Task Force definitions.