Root Element (for use in XML). It consists of all metadata transferred in an interchange. The metadata consists of two parts: Protocol package (information needed by the protocol to function); and, Profile Package (information relating to the agents involved in the transaction). May be omitted if ForwardToken or RequestPatronRedirect is supplied. Really unbounded? Language (http://www.loc.gov/standards/iso639-2/langcodes.html) Currency (http://www.xe.com/iso4217.htm)