Get Page ID

I am running modx 0.9.5
Can I get the Page id from a page.
I can get pagetitle like $title = $modx->documentObject[’pagetitle’]
also posible to get the parent id like $parent = $modx->documentObject[’parent’]

but this one throughs an error

$siteid = $modx->documentObject[’id’]

any help appreciated

for get the id use $modx->documentIdentifier
for others fields
$doc=$modx->getDocument($theidofthedocument,’parent,pagetitle’;
echo ’ouput pagetitle’.$doc[’pagetitle’];
think it help you ;-)