Determine. To establish enough information about taxable products at the time of removal to calculate the tax, specifically the quantity (pounds or number) and kind (for example, cigarettes, snuff, paper tubes). Where the tax rate depends on additional information (such as number of cigarette papers to a set before January 1, 2000 or sale price of large cigars), that information must also be established as part of tax determination.
27 CFR § 40.11
When used in this part and in forms prescribed under this part, the following terms shall have the meanings given in this section, unless the context clearly indicates otherwise. Words in the plural form shall include the singular, and vice versa, and words indicating the masculine gender shall include the feminine. The terms includes and including do not exclude things not listed which are in the same general class.