The Printers International Union reached agreement for a new three-year contract with a large regional printing company. As was their practice, the union negotiators then met with Sullivan Brothers Printers, Inc., a small specialty shop employing 10 union printers, and Sullivan Brothers and the union agreed to follow the contractual pattern set by the union and the large printing company. That is, Sullivan Brothers agreed to give its workers all of the benefits negotiated for the employees of the large printing company. When the contract was typed, a new benefit of 75 percent employer-paid coverage for a dental plan was inadvertently omitted from the final contract the parties signed. The mistake was not discovered until six months after the contract took effect. Sullivan Brothers Printers, Inc., is reluctant to assume the additional expense. It contends that the printed copy, which does not cover dental benefits, must control. The union believes that clear and convincing evidence shows an inadvertent typing error. Decide.