Lisa and Darrell Miller were married with two children. They divorced and entered into a joint custody agreement. Under this agreement, Darrell agreed to set funds away to cover their minor children’s college expenses. The agreement was clear as to what college expenses were covered but vague on such issues as how much was to be paid, when Darrell was to start paying, for how long, and— as a matter of fact— whether he had to pay at all. Lisa, the ex- wife, insisted that he must pay the children’s college expenses, but could not back up her request with any real evidence other than what was stated in the contract that was under dispute. Is Darrell legally obligated to pay?