Certificate holder means a manufacturer (including importers) with a valid certificate of conformity for at least one family in a given model year, or the preceding model year. Note that only manufacturers may hold certificates. Your applying for or accepting a certificate is deemed to be your agreement that you are a manufacturer.
40 CFR § 1068.30
The following definitions apply to this part. The definitions apply to all subparts unless we note otherwise. All undefined terms have the meaning the Clean Air Act gives to them. The definitions follow: