7 C.F.R. § 319.40-3
(a) Canada and Mexico.
(1) The following articles may be imported into the United States under general permit:
(i) From Canada: Regulated articles, other than the following:
(b) Regulated wood packaging material. Regulated wood packaging material, whether in actual use as packing for regulated or nonregulated articles or imported as cargo, may be imported into the United States under a general permit in accordance with the following conditions:
(2) Marking. The wood packaging material must be marked in a visible location on each article, preferably on at least two opposite sides of the article, with a legible and permanent mark that indicates that the article meets the requirements of this paragraph. The mark must be approved by the International Plant Protection Convention in its International Standards for Phytosanitary Measures to certify that wood packaging material has been subjected to an approved measure, and must include a unique graphic symbol, the ISO two-letter country code for the country that produced the wood packaging material, a unique number assigned by the national plant protection agency of that country to the producer of the wood packaging material, and an abbreviation disclosing the type of treatment (e.g., HT for heat treatment or MB for methyl bromide fumigation). The currently approved format for the mark is as follows, where XX would be replaced by the country code, 000 by the producer number, and YY by the treatment type (HT or MB):

(4) Exception for Department of Defense. Regulated wood packaging material used by the Department of Defense (DOD) of the U.S. Government to package nonregulated articles, including commercial shipments pursuant to a DOD contract, may be imported into the United States without the mark required by paragraph (b)(2) of this section.
(Approved by the Office of Management and Budget under control numbers 0579-0049 and 0579-0225)
(e) Regulated articles the permit process has determined to present no plant pest risk. Regulated articles for which a specific permit has been issued in accordance with § 319.40-4(b)(2)(i) may be imported without other restriction under this subpart, except that they are subject to the inspection and other requirements in § 319.40-9.
(Approved by the Office of Management and Budget under control numbers 0579-0049 and 0579-0257)
[60 FR 27674, May 25, 1995, as amended at 63 FR 50110, Sept. 18, 1998; 63 FR 69542, Dec. 17, 1998; 69 FR 52418, Aug. 26, 2004; 69 FR 55732, Sept. 16, 2004; 69 FR 61587, Oct. 20, 2004; 71 FR 57386, Sept. 29, 2006; 72 FR 30462, 30467, June 1, 2007; 75 FR 4251, Jan. 26, 2010; 85 FR 61809, Oct. 1, 2020]