status registry missing code 506

Hi,

I just noticed that RFC2295 (Transparent Content Negotiation in HTTP) 
defines status code 506 
(<http://tools.ietf.org/html/rfc2295#section-8.1>), but that code is 
missing in the IANA registry 
(<http://www.iana.org/assignments/http-status-codes>).

Should we just request registration?

Best regards, Julian