A computer data signal including a generic element identifier, a plurality of task-specific data, a variable length identifier and a multi-use data type identifier. A caller can connect to an automated telephone answering service, and download the service’s call tree. A second step generates an output image which gives a different visual impression of the object than the first image and the second image, based on difference data of the specular reflection components extracted from the first image and the second image. The guide element at an end thereof is joined to the base and the driving element passes through the guide element.