function getPlotsSelectedIDStr(formid, checkid) {
    var formobj = document.getElementById( formid );
    //alert(form.name);
		if ( formobj ) {
      var result = '', comma = '';
      for ( var i = 0; i < formobj.length; ++i ) {
        var here   = formobj.elements[ i ];
//alert((here.id.substr(0,9))+"*"+checkid);
        if ( ( here.type == 'checkbox' ) && ((here.id.substr(0,checkid.length)) == checkid) && (here.checked) ) {
//alert("ticked");
          result += comma + here.value;
          comma  = '_';
        }
      }
      //alert( 'Selected: ' + result );
   		return(result);
			} else {
      alert( 'Form not found: id = "' + formid + '"' );
			return("");
			}
  }