Instruments evidencing ownership interests in personal property, such as bills of sale or simple contracts of sale of personal property, usually are not registered, but may be registered.  (See T.C.A. § 66-24-101 for a listing of most instruments eligible for registration.)  All agreements for the conveyance of real or personal property are eligible for registration.  T.C.A. § 66-24-101(a)(1) & (5).