This subtitle does not apply to sales, use, storage, or consumption by any person who registers under or complies with <cite data-doc="Md. Code" data-path="27|281">Article 27, § 281 of the Maryland Code</cite>, or any person who otherwise complies with that section of the Code. The burden of proof of an exemption is upon the person claiming it. City Code, 1976/83, art. 28, §79 Ord. 86-687