The specification for URLs, RFC1738, limits the use of allowed characters to only a limited subset of the US-ASCII character set (2.2 URL Character Encoding Issues): quot;The lower case letters "a"--"z", digits, and the characters plus ("+"), period("."), and hyphen ("-") are allowed...

A valid URL address consists of the name and location of your site. Example: http://www.yoursite.com.

au 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 webname and you cannot have two hyphens in a row. Spaces and special characters (such as !, $, &, ?, and so on) are never permitted. The minimum length is 2 characters and the maximum length is 63 characters (excluding the "http://www" portion).

A:The only valid characters for a domain name are letters, numbers and a hyphen "-". Other special characters like the underscore "_" or the exclamation mark "!" are not permitted. A domain name can be up to 63 characters long, plus the characters used to identify the Top Level Domain (.com, .ca, .biz, .info, .net, .org). Do not include the www. before your domain name when counting characters.

MOBI domain 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 !, $, &, ?, and so on) are never permitted.

Dotmobi domain 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 valid characters are english alphabetical letter(a-z), number(0-9), hyphen(-) and underscore(_). The length of your subdomain name can be 3~33 characters.

When creating a new server, enter a name that does not contain any special characters. Some products or applications that use the server name such as Digital Certificate Manager cannot handle the use of special characters. A server name must begin with an alphabetic character and must not be longer than ten characters.

A domain name can be up to 67 characters long -- including the 4 characters used to identify the Top Level Domain (.NET, .COM, .ORG, or .EDU). The only valid characters for a domain name are letters, numbers and a hyphen "-".