Arabians When naming the Arabian the registration rules are as such; No horse will be registered by a name which has exactly the same spelling as a name already registered, which has numerical prefixes or suffixes, or which has the suffix "Sr." or "Jr.". The only valid characters are capital letters A through Z, dash and space. Punctuation, apostrophes, and diacritical markings or symbols may not be used. Names may not contain more than 21 total characters or be composed of more than four parts. Horses born before 2002 are limited to 17 characters and three parts in a name.