37 C.F.R. § 1.74 Reference to drawings.
Title 37 - Patents, Trademarks, and Copyrights
When there are drawings, there shall be a brief description of the several views of the drawings and the detailed description of the invention shall refer to the different views by specifying the numbers of the figures and to the different parts by use of reference letters or numerals (preferably the latter).
Title 37: Patents, Trademarks, and Copyrights
PART 1—RULES OF PRACTICE IN PATENT CASES
Subpart B—National Processing Provisions
Specification
§ 1.74 Reference to drawings.
