The present invention relates to fosamprenavir calcium substantially free of isomer impurity, tetrahydro-3-furanyl-3-sulfonylamino-1-benzyl-2-propyl carbamate, and its process for preparation thereof. Each of the belts includes a plurality of spaced-apart fingers which engage the edges of the stacked sheet material and define a pocket therebetween. The first window is ordinarily displayed after at least one file has been copied onto the clipboard and a second file is selected to be copied. The first internal electrode consists of plural types of first internal electrodes and the plural types of first internal electrodes have their respective first lead portions at different positions. This limits the power consumption of the oscillator unit throughout the range of frequency control.