What is "validationdata"

[Guido1982]

Again, as to not pollute the "PackingSlip" thread with global questions:

What does this part do:

PHP Code:

$tabid = getTabid("PackingSlip");
$validationData = getDBValidationData($focus->tab_name, $tabid);
$data = split_validationdataArray($validationData);
$category = getParentTab();
$smarty->assign("CATEGORY", $category); 


Found here. Are all these functions native app functions?