From the RDA-list:
Changes to the Source Codes for Vocabularies, Rules, and Schemes
In making available changes to MARC to accommodate RDA, the Library of Congress published lists of terms and codes for RDA content, media, and carrier types. Upon further consideration we have determined that the source codes do not adequately reflect the source material (RDA) as is usually the case. Therefore, before the beginning of the RDA tests and use of these codes, they have been changed to conform to the common pattern. The new codes have replaced the ones formerly indicated in the Source Codes for Vocabularies, Rules, and Schemes list for Genre/Form Term and Code Sources. See the genre/form source code list for current usage in MARC fields and MODS/MADS elements.
The new codes may be used immediately for RDA records.
Genre/Form Term and Code Source Codes
The following source codes have been changed on the Genre/Form Code and Term Source Codes list (http://www.loc.gov/standards/sourcelist/genre-form.html).
rdacarrier (formerly marccarrier)
Term and code list for RDA carrier types
rdacontent (formerly marccontent)
Term and code list for RDA content types
rdamedia (formerly marcmedia)
Term and code list for RDA media types
The names of the respective value lists have also been changed to those indicated above in order to reflect their content (see the listing of value lists, Value Lists for Codes and Controlled Vocabularies).
The Library of Congress, Network Development and MARC Standards Office provides information about existing and newly assigned source and value codes on its Web site.
Network Development and MARC Standards Office
101 Independence Ave., S.E.
Washington, DC 20540-4402 U.S.A.