317.2.i The official establishment number of the official establishment in which the product was processed under inspection shall be placed as follows:

317.2.i.1 Within the official inspection legend in the form required by part 312 of this subchapter; or

317.2.i.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 "EST"; or

317.2.i.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 material 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 "EST. No. on Metal Clip" or "Est. No. on Pan", if shown in a prominent and legible manner in a size sufficient to insure easy visibility and recognition; or

317.2.i.4 On an insert label placed under a transparent covering if clearly visible and legible and accompanied by the prefix "EST".