What are the valid characters and valid lengths for domain names?

.INFO names can contain the English-language letters A through Z, and the digits 0 through 9. You can also use hyphens, but hyphens cannot begin or end your domain name. Spaces and special characters (such as !, $, &, ë, and so on) are never permitted. The minimum length is 3 characters, and the maximum length is 63 characters (excluding the "http://www" and ".info" portions).

At this time, .INFO supports some multilingual domain names in foreign character sets. Please see more information here.