determines that the deletion should not be permitted the flow is ended incidentally when the operator transmits the data and this deletion process is executed again the deletion can be immediately made in the transmitting unit 6 when a transmission request processing unit 6 a obtains a transmission request from the operator a transmission determination processing unit 6 b determines whether or not the transmission is to be permitted and a transmission history data storing unit 6 c and an external data signal processing unit 6 d store the result in the third memory 1 c as shown in fig5 in the transmission determination processing unit 6 b the change history data is obtained in response to the transmission request from the operator step s 31 the completion of the program after the change history is determined step s 32 and for example the presence absence of a grammar error or the like is determined step s 33 and when there is no error a transmission process is executed step s 34 when there is an error a warning process is executed step s 35 in which the operator is given a warning that the program including the error will be transmitted to the external device or the.