49 CFR § 172.320 - Explosive hazardous materials.
(a) Except as otherwise provided in paragraphs (b), (c), (d) and (e) of this section, each package containing a Class 1 material must be marked with the EX-number for each substance, article or device contained therein.
(b) Except for fireworks approved in accordance with § 173.64 of this subchapter, a package of Class 1 materials may be marked as follows, in lieu of the EX number required by paragraph (a) of this section:
(1) With a national stock number issued by the Department of Defense or identifying information, such as a product code required by regulations for commercial explosives specified in 27 CFR part 555, if the national stock number or identifying information can be specifically associated with the EX number assigned; or
(2) For Division 1.4G consumer fireworks reviewed by a Fireworks Certification Agency approved in accordance with 49 CFR part 107 subpart E and certified in accordance with § 173.65, with the FC number assigned by a DOT-approved Fireworks Certification Agency.
(c) When more than five different Class 1 materials are packed in the same package, the package may be marked with only five of the EX-numbers, national stock numbers, product codes, or combination thereof.
(d) The requirements of this section do not apply if the EX number, FC number, product code or national stock number of each explosive item described under a proper shipping description is shown in association with the shipping description required by § 172.202(a). Product codes and national stock numbers must be traceable to the specific EX number assigned by the Associate Administrator or FC number assigned by a DOT-approved Fireworks Certification Agency.
(e) The requirements of this section do not apply to the following Class 1 materials:
(1) Those being shipped to a testing agency in accordance with § 173.56(d) of this subchapter;
(2) Those being shipped in accordance with § 173.56(e) of this subchapter, for the purposes of developmental testing;
(5) Those that are transported in accordance with § 173.56(c)(2) of this subchapter and, therefore, are covered by a national security classification currently in effect.