The value must conform to BCP 47. If the value is a private use code (i.e., starts
with x- or contains -x-) it should, and if not it may, match the
value of an ident attribute of a language element supplied in the TEI
Header of the current document.
any string of characters; if the typographic rendition of a text is to be
systematically recorded, a systematic set of values for the rend attribute should
be defined.
<head rend="align(center) case(allcaps)"> <lb/>To The <lb/>Duchesse <lb/>of <lb/>Newcastle, <lb/>On Her <lb/> <hi rend="case(mixed)">New Blazing-World</hi>. </head>
rendition
points to a description of the rendering or presentation used for this element in the
source text.