9 CFR § 590.413 - Form of official identification symbol and inspection mark.
The shield set forth in Figure 1 of this section containing the letters “USDA” must be the official identification symbol used in connection with egg products to denote that the official plant receives official inspection service. The inspection mark used on containers of edible egg products is set forth in Figure 1 of this section, except that the plant number may be preceded by the letter “G” in lieu of the word plant. The plant number may also be omitted from the official mark if applied on the container's principal display panel or other prominent location and preceded by the letter “G.” 76
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