Readability\Readability::initializeNode PHP Method

    protected function initializeNode($node)
    {
        if (!isset($node->tagName)) {
            return;
        }
        $readability = $this->dom->createAttribute('readability');
        // this is our contentScore
        $readability->value = 0;
        $node->setAttributeNode($readability);
        // using strtoupper just in case
        switch (strtoupper($node->tagName)) {
            case 'ARTICLE':
                $readability->value += 15;
            case 'DIV':
                $readability->value += 5;
                break;
            case 'PRE':
            case 'CODE':
            case 'TD':
            case 'BLOCKQUOTE':
            case 'FIGURE':
                $readability->value += 3;
                break;
            case 'SECTION':
                // often misused
                // $readability->value += 2;
                break;
            case 'OL':
            case 'UL':
            case 'DL':
            case 'DD':
            case 'DT':
            case 'LI':
                $readability->value -= 2 * round($this->getLinkDensity($node), 0, PHP_ROUND_HALF_UP);
                break;
            case 'ASIDE':
            case 'FOOTER':
            case 'HEADER':
            case 'ADDRESS':
            case 'FORM':
            case 'BUTTON':
            case 'TEXTAREA':
            case 'INPUT':
            case 'NAV':
                $readability->value -= 3;
                break;
            case 'H1':
            case 'H2':
            case 'H3':
            case 'H4':
            case 'H5':
            case 'H6':
            case 'TH':
            case 'HGROUP':
                $readability->value -= 5;
                break;
        }
        $readability->value += $this->getWeight($node);
    }