public function renderDefinition()
    {
        $stream = $this->_rtf->getWriter();
        if ($this->isVerticalMerged()) {
            if ($this->isVerticalMergedFirstInRange()) {
                $stream->write('\clvmgf');
            }
            else {
                $stream->write('\clvmrg');
            }
        }

        $backgroundColor = $this->getBackgroundColor();
        if ($backgroundColor) {
            $colorTable = $this->_rtf->getColorTable();
            $stream->write('\clcbpat' . $colorTable->getColorIndex($backgroundColor) . ' ');
        }

        switch ($this->getVerticalAlignment()) {
            case self::VERTICAL_ALIGN_TOP:
                $stream->write('\clvertalt');
                break;

            case self::VERTICAL_ALIGN_CENTER:
                $stream->write('\clvertalc');
                break;

            case self::VERTICAL_ALIGN_BOTTOM:
                $stream->write('\clvertalb');
                break;
        }

        switch ($this->getRotateTo()) {
            case self::ROTATE_RIGHT:
                $stream->write('\cltxtbrl');
                break;

            case self::ROTATE_LEFT:
                $stream->write('\cltxbtlr');
                break;
        }

        // NOTE: microsoft and all other rtf readers I know confound left with top cell padding
        if ($this->_paddingLeft) {
            $stream->write('\clpadft3\clpadt' . PHPRtfLite_Unit::getUnitInTwips($this->_paddingLeft) . ' ');
        }
        if ($this->_paddingTop) {
            $stream->write('\clpadfl3\clpadl' . PHPRtfLite_Unit::getUnitInTwips($this->_paddingTop) . ' ');
        }
        if ($this->_paddingBottom) {
            $stream->write('\clpadfb3\clpadb' . PHPRtfLite_Unit::getUnitInTwips($this->_paddingBottom) . ' ');
        }
        if ($this->_paddingRight) {
            $stream->write('\clpadfr3\clpadr' . PHPRtfLite_Unit::getUnitInTwips($this->_paddingRight) . ' ');
        }

        $border = $this->getBorder();
        if ($border) {
            $stream->write($border->getContent('\cl'));
        }
    }