PURPOSE: To eliminate the trouble of parameter specification and vary parameters even halfway in a program by setting or varying optional parameters, stored in the record of a specific identifier, together in the NC program.

CONSTITUTION: A constant format consisting of a group of elements of plural parameters is called a 'record' and a parameter element is called a 'member'. A constant format consisting of a group of members of parameters such as a time constant of acceleration or deceleration and a maximum speed is stored as record type members to be generated. Further, identifiers RM1 and RM2 are specified for the record in which the parameters are stored. Thus, the record identifiers are called in the NC program to vary an optional number of parameters together. Further, the parameters are varied in the program, so this method can answer to a different object of machining.