This version adds a new cataloging check to the 336, 337 and 338 fields that crosschecks the concepts described in the subfield $a (Term) and subfield $b (Code) and produces an error message if they are not describing the same concept. This check requires that both $a and $b be present, and that the $2 contain one of the RDA terms (rdacontent, rdamedia, or rdacarrier). One
recommendation is that different concepts should be described in separate occurrences of the tag. This recommendation will reduce the amount of confusion that might occur when $0 and $1 begin to be added to these fields.