CListFieldList::_read_form_settings

protected function _read_form_settings($form_id)
{
	if(!$form_id)
		return null;

	global $DB;

	//read list meta from module table
	$rsFields = $DB->Query("
		SELECT * FROM b_lists_field
		WHERE IBLOCK_ID = ".$this->iblock_id."
		ORDER BY SORT ASC
	", false, "File: ".__FILE__."
Line: ".__LINE__);
	$dbFields = array();
	while($arField = $rsFields->Fetch())
		$dbFields[$arField["FIELD_ID"]] = $arField;

	$fields = array();
	$customTabs = CUserOptions::GetOption("form", $form_id);

	//read list meta from interface settings
	if($customTabs && $customTabs["tabs"])
	{
		$sort = 10;
		$arTabs = explode("--;--", $customTabs["tabs"]);
		foreach($arTabs as $customFields)
		{
			if($customFields)
			{
				$arCustomFields = explode("--,--", $customFields);
				array_shift($arCustomFields);
				foreach($arCustomFields as $customField)
				{
					list($FIELD_ID, $customName) = explode("--#--", $customField);
					if($FIELD_ID != "SECTIONS")
					{
						$customName = ltrim($customName, "* -xa0");

						if(CListFieldTypeList::IsField($FIELD_ID))
							$obField = $fields[$FIELD_ID] = new CListElementField($this->iblock_id, $FIELD_ID, $customName, $sort);
						else
							$obField = $fields[$FIELD_ID] = new CListPropertyField($this->iblock_id, $FIELD_ID, $customName, $sort);

						//check if property was deleted from admin interface
						if(!is_array($obField->GetArray()))
						{
							unset($fields[$FIELD_ID]);
						}
						else
						{
							$sort += 10;
							unset($dbFields[$FIELD_ID]);
						}
					}
				}
			}
		}
		//There were some fields "deleted" from interface
		foreach($dbFields as $FIELD_ID => $arField)
		{
			$DB->Query("
				DELETE FROM b_lists_field
				WHERE IBLOCK_ID = ".$this->iblock_id."
				AND FIELD_ID = '".$DB->ForSQL($FIELD_ID)."'
			", false, "File: ".__FILE__."
Line: ".__LINE__);
		}
	}
	else//or from module metadata
	{
		foreach($dbFields as $FIELD_ID => $arField)
		{
			if(CListFieldTypeList::IsField($FIELD_ID))
				$obField = $fields[$FIELD_ID] = new CListElementField($this->iblock_id, $FIELD_ID, $arField["NAME"], $arField["SORT"]);
			else
				$obField = $fields[$FIELD_ID] = new CListPropertyField($this->iblock_id, $FIELD_ID, $arField["NAME"], $arField["SORT"]);
			//check if property was deleted from admin interface
			if(!is_array($obField->GetArray()))
			{
				unset($fields[$FIELD_ID]);
				$DB->Query("
					DELETE FROM b_lists_field
					WHERE IBLOCK_ID = ".$this->iblock_id."
					AND FIELD_ID = '".$DB->ForSQL($FIELD_ID)."'
				", false, "File: ".__FILE__."
Line: ".__LINE__);
			}
		}
	}

	return $fields;
}