PURPOSE: To exactly and efficiently set a destination by preventing an erroneous destination from being set by a user, and shortening the time spent for an input work, at the time of constituting the destination having a prescribed format, used on a communication system of an electronic computer.

CONSTITUTION: At the time of inputting an arbitrary attribute value to an input area, an input value checking means 4 checks whether its character or character-string is appropriate to its attribute or not. Also, with respect to the whole input value extending over plural attributes, as well, appropriateness of the value is checked, and the erroneous input of the destination by a user is prevented.