Google Merchant как создать файл импорта товаров в xml / txt

This page contains the following errors:
error on line 1 at column 2: StartTag: invalid element name
Below is a rendering of the page up to the first error.

<?php
$filename = MODX_BASE_PATH . 'gmerch.xml';
$limit='1000';
$offset='0';
$tpl = '@INLINE <item>
  <title>{$pagetitle}</title>
  <link>'.MODX_BASE_PATH.'/{$uri}</link>
  <description>{$introtext | striptags}</description>
  <g:image_link>'.MODX_BASE_PATH.'/{$image}</g:image_link>
  <g:price>{$price}</g:price>
  <g:id>{$article}</g:id>
  <g:brand>{$_pls["vendor.name"]}</g:brand>
  <g:condition>new</g:condition>
</item>';

$data = '<?xml version="1.0"?>
<rss version="2.0" xmlns:g="http://base.google.com/ns/1.0">
<channel>
<title>Название</title>
<link>'.MODX_BASE_PATH.'</link>
<description>Описание</description>'; 
$data .= $modx->runSnippet('msProducts', array(
       'parents' => 0, 'where' => '{"Data.favorite":1, "alias:!=":""}', 'limit' => $limit, 'offset' => $offset, 'tpl' => $tpl, 'includeThumbs'=> '600x600', 'includeContent' => 1, 'includeTVs' => 'img,image'
    ));

$data = '</channel></rss>';

$filename = MODX_BASE_PATH . 'gmerch.xml';
$fp = fopen($filename, 'a');
fwrite($fp, $data);
fclose($fp);