You are trying to register a domain that is graphically identical to an already registered domain name in another language. For example: if the domain pear.org (Latin characters) is registered, then the registration of the реаг.org domain (Cyrillic characters) will be unavailable, respectively, and vice versa, if the domain реаг.org (Cyrillic characters) is registered, then registering the domain pear.org (Latin characters) will not be possible.