function _beginpage($orientation, $size)
{
parent::_beginpage($orientation, $size);
if ($this->NewPageGroup) {
// start a new group
$n = sizeof($this->PageGroups) + 1;
$alias = '{' . $n . '}';
$this->PageGroups[$alias] = 1;
$this->CurrPageGroup = $alias;
$this->NewPageGroup = false;
} elseif ($this->CurrPageGroup) {
$this->PageGroups[$this->CurrPageGroup]++;
}
}