The
lang
function returns true or false depending on whether the language of the context node as specified by
xml:lang
attributes is the same as or is a sub-language of the language specified by the argument string. The language of the context node is determined by the value of the
xml:lang
attribute on the context node, or, if the context node has no
xml:lang
attribute, by the value of the
xml:lang
attribute on the nearest ancestor of the context node that has an
xml:lang
attribute. If there is no such attribute, then
lang
returns false. If there is such an attribute, then
lang
returns true if the attribute value is equal to the argument ignoring case, or if there is some suffix starting with - such that the attribute value is equal to the argument ignoring that suffix of the attribute value and ignoring case.