function cng_img(img_no){
switch(img_no){
case 10: document.images["img1"].src='button10.gif'; break;
case 11: document.images["img1"].src='button11.gif'; break;
case 12: document.images["img1"].src='button12.gif'; break;
case 20: document.images["img2"].src='button20.gif'; break;
case 21: document.images["img2"].src='button21.gif'; break;
case 22: document.images["img2"].src='button22.gif'; break;
case 30: document.images["img3"].src='button30.gif'; break;
case 31: document.images["img3"].src='button31.gif'; break;
case 32: document.images["img3"].src='button32.gif'; break;
case 40: document.images["img4"].src='pdficon10.gif'; break;
case 41: document.images["img4"].src='pdficon11.gif'; break;
case 42: document.images["img4"].src='pdficon12.gif'; break;
case 50: document.images["img5"].src='pdficon10.gif'; break;
case 51: document.images["img5"].src='pdficon11.gif'; break;
case 52: document.images["img5"].src='pdficon12.gif'; break;
case 60: document.images["img6"].src='button60.gif'; break;
case 61: document.images["img6"].src='button61.gif'; break;
case 62: document.images["img6"].src='button62.gif'; break;
case 70: document.images["img7"].src='button60.gif'; break;
case 71: document.images["img7"].src='button61.gif'; break;
case 72: document.images["img7"].src='button62.gif'; break;
default: break;}
}