public function getVirtualFields()
    {
        // Check if copied page exists
        $record = $this->CopyContentFrom();
        if (!$record || !$record->exists()) {
            return array();
        }

        // Diff db with non-virtual fields
        $fields = array_keys(static::getSchema()->fieldSpecs($record));
        $nonVirtualFields = $this->getNonVirtualisedFields();
        return array_diff($fields, $nonVirtualFields);
    }