A person may not use a vessel unless: It has a number issued on a certificate of number by the Department or the issuing authority in the state where the vessel is principally used; or The vessel is exempt from numbering pursuant to 33 CFR §173.13 as amended. Display. The number shall conform to the requirements of 33 CFR §174.23 as amended. The first part shall consist of the letters “MD”; The second part shall consist of not more than four Arabic numerals; The third part shall consist of not more than two letters; The parts shall be separated by a hyphen or an equivalent space, for example: MD-1-A, MD-1234-AA, MD 56 AA; and Letters “I”, “O” and “Q” may not be used in the suffix. Each number shall be displayed pursuant to 33 CFR §173.27 as amended. Painted on or permanently attached to each side of the forward half of the vessel except as allowed by §B(3), of this regulation, or required by §B(4), of this regulation; Plain vertical block characters not less than 3 inches high; Contrast with the color of the background and be distinctly visible and legible; and Read from left to right. A manufacturer or dealer, but not a broker, may apply to the Department for the issuance of certificates of number to be used for testing or demonstrating vessels. Vessel number shall end with the suffix “DL”. There can be no personal use of a vessel displaying a “DL” number. The number may be painted on or attached to removable plates that are temporarily but firmly attached to the side of the forward half of the vessel. On vessels so configured that a number on the hull or superstructure would not be easily visible, the number shall be painted on or attached to a backing plate that is attached to the forward half of the vessel so that the number is visible from each side of the vessel. Other numbers may not be carried on the forward half of the vessel. Except as provided in Regulation .04, a person may not use a vessel unless: It has a number issued on a certificate of number by the Department or the issuing authority in the state where the vessel is principally used; and The number is displayed as required by regulation §B, of this regulation. This regulation does not apply to a vessel for which a valid temporary certificate has been issued to its owner by the issuing authority in the state in which the vessel is principally used.