9 CFR 381.123 Official inspection mark; official establishment number
The immediate container of every inspected and passed poultry product shall bear:

381.123.a The official inspection legend; and

381.123.b The official establishment number of the official establishment in which the product was processed under inspection and placed as follows:

381.123.b.1 Within the official inspection legend in the form required by Subpart M of this part; or

381.123.b.2 Outside the official inspection legend elsewhere on the exterior of the container or its labeling, e.g., the lid of a can, if shown in a prominent and legible manner in a size sufficient to insure easy visibility and recognition and accompanied by the prefix "P"; or

381.123.b.3 Off the exterior of the container, e.g., on a metal clip used to close casings or bags, or on the back of a paper label of a canned product, or on other packaging or labeling in the container, e.g., on aluminum pans and trays placed within containers, when a statement of its location is printed contiguous to the official inspection legend, such as "Plant No. on Package Closure" or "Plant No. on Pan", if shown in a prominent and legible manner in a size sufficient to ensure easy visibility and recognition; or

381.123.b.4 On an insert label placed under a transparent covering if clearly visible and legible and accompanied by the prefix "P".