official formula n.
A chemical formula for a pharmaceutical or compound, especially one contained in the U.S. Pharmacopeia or the National Formulary.
This, I presume, was the official formula customary in the Lombard Inquisition.
Both begin with the official formula, and are dated the 18th of January, 1292 (1293, new style).
An official formula of one year might blossom out the next in a fancy bottle bearing a proprietor's name.