MARC was registered a long time ago.
http://www.faqs.org/rfcs/rfc2220.html
Some of the text is a bit dated and could stand some updating.

Patrick is right that an XML schema such as MODS or MARCXML would be text/xml.

Rebecca

Rebecca S. Guenther                                                       
 Senior Networking and Standards Specialist                  
 Network Development and MARC Standards Office     
 Library of Congress   
 101 Independence Ave. SE                                       
 Washington, DC 20540                                                      
 Washington, DC 20540-4402                                          
 (202) 707-5092 (voice)    (202) 707-0115 (FAX)           
 [log in to unmask]
>>> Patrick Yott <[log in to unmask]> 02/04/09 10:59 AM >>>
Not sure about the binary MARC, but all flavors of xml should be typed to
either text/xml or application/xml, yes?

patrick


On 2/4/09 10:47 AM, "Jonathan Rochkind" <[log in to unmask]> wrote:

> I am actually rather shocked that it seems that MARC-XML, MODS,
> MARC21-binary, do not have registered Internet Content Types (aka MIME
> types).
> 
> Am I missing something, or is this really so?
> 
> Anyone know what the process is for registering such?  Anyone want to
> help try to do that? I guess we'd probably have to talk to the standards
> organizations for each of those types, rather than doing it independently?
> 
> Jonathan