9 C.F.R. § 145.4
(d) Except as provided by this paragraph, participants in the Plan may not buy or receive products for any purpose from nonparticipants unless they are part of an equivalent program, as determined by the Official State Agency. Participants in the Plan may buy or receive products from flocks that are neither participants nor part of an equivalent program, for use in breeding flocks or for experimental purposes, under the following conditions only:
(e) Each participant shall be assigned a permanent approval number by the Service. This number, prefaced by the numerical code of the State, will be the official approval number of the participant and may be used on each certificate, invoice, shipping label, or other document used by the participant in the sale of his products. Each Official State Agency which requires an approval or permit number for out-of-State participants to ship into its State should honor this number. The approval number shall be withdrawn when the participant no longer qualifies for participation in the Plan.
(Approved by the Office of Management and Budget under control number 0579-0057)
[36 FR 23112, Dec. 3, 1971, as amended at 38 FR 13706, May 24, 1973; 41 FR 48723, Nov. 5, 1976. Redesignated at 44 FR 61586, Oct. 26, 1979, as amended at 47 FR 21991, May 20, 1982; 48 FR 57473, Dec. 30, 1983; 57 FR 57341, Dec. 4, 1992; 83 FR 28352, June 19, 2018]