function switch_layer_vis(id) {

      var max = 20;
      var suffix = "info_";

      if(id == 0) {
         for(i=1;i<=max;i++) {
            if(document.getElementById(suffix+i)) document.getElementById(suffix+i).style.display = "none";
         }
      } else {
         if(document.getElementById(suffix+id).style.display == "none") {
            for(i=1;i<=max;i++) {
               if(document.getElementById(suffix+i)) {
                  document.getElementById(suffix+i).style.display = "none";
                  document.getElementById(suffix+id).style.display = "inline";
               }
            }
   	   } else {
   	      document.getElementById(suffix+id).style.display = "none";
         }
   	}
   }