A method of mirroring data to a mirrored to port in a plurality of switches. Differentially encoded space-time output blocks, for transmission via a plurality of transmit antennas of a wireless communications system, are produced by multiplying each space-time block from the space-time block coder by the respective previous differentially encoded space-time output block. A masking layer is preferably spaced above a substrate, where the masking layer has at least one aperture therein. Specifically disclosed is a process for producing nitroisourea derivatives represented by the following general formula, which is characterized in that nitroisourea derivatives represented by the following general formula and amines represented by the following general formula or a salt thereof are reacted in the presence of a catalytic amount of a hydrogen carbonate,. The information code producing apparatus detects the size of this free space by, at least, either selection from a plurality of candidate shapes prepared in advance or input of shape designating information provided from the outside.