<p>The lever body 17 includes a recess (receiver) 66 defined by an upper plate 70 and the projections 65a, 65b, as shown in FIG. 7. A notch 67 is formed in the upper plate 70 (see FIG. 1). The notch 67 permits the first locking piece 61 to move from its retreating position to the operating position in the recess 66. The dimension of the notch 67 in the Y direction (the width of the notch 67) and the dimension of the notch 67 in the notch X direction (the depth of the notch 67) are both shorter than the corresponding dimensions of the recess 66. The upper plate 70 functions as a prohibiting member.</p>
