public function addSection(array $aSectionset)
{
$aSectionset = $aSectionset + array('section_id' => null);
$aSectionset['section_id'] = $this->sanitizeSlug($aSectionset['section_id']);
$this->aSectionsets[$aSectionset['section_id']] = $aSectionset;
$this->aFieldsets[$aSectionset['section_id']] = $this->getElement($this->aFieldsets, $aSectionset['section_id'], array());
}