how to register a domain name as http://del.icio.us/?

How do I create such domain name as http://del.icio.us/? Is it just a sub-domain, and resumed from icio.us? I do not think that we can register domain names with "." Does anyone have experience?

This is a subdomain off icio.us. You can not register domain names. 'S on them.

How to Register a Domain Name

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