The invention relates to a compact two-group zoom optical system which has an angle of view of 70\xb0 or greater at the wide-angle end and satisfactory image-formation capability all over the zoom range while maintaining a zoom ratio of 3 or greater. The first transmission schedule allocates bandwidth for the first network node to transmit data to a second network node. A method for sealing the pores of a porous PET graft includes the step of coating at least one surface of said graft with at least one polyurethane, or mixtures and combinations thereof. In a case where the user inputs the disclosure statement into one of the input forms of the plurality of disclosure items, second input control means inputs, into the input form, the disclosure statement that is input into the input form of another disclosure item associated with the disclosure item.