The sheets of tracing cloth on which copies of the original plats and plans are made shall be not less than thirty by twenty inches [762.00 by 508.00 millimeters] nor more than thirty-one by twenty-one inches [787.40 by 533.40 millimeters] and shall be lettered in a workmanlike manner with suitable titles transcribed on them, numbered, lettered, and made up in one or more books which are bound in suitable covers so that they may be readily removed for the purpose of making prints. These copies shall serve as negatives for prints and shall be certified by the engineer in charge of the work to be correct copies of the original.
N.D.C.C. § 11-24-02