All business with the Office must be transacted in writing. The action of the Office will be based exclusively on the written record. No consideration will be given to any alleged oral promise, stipulation, or understanding when there is disagreement or doubt. 37 C.F.R. §2.191 84 FR 37096, July 31, 2019 81 FR 69987, 1/14/2017; 84 FR 37096, 10/5/2019 Part 3 pertaining to both patents and trademarks is placed in the grouping pertaining to patents regulations. Part 4 is placed in the separate grouping