Whether every RSS source have only one channel?

Question

There is a example of RSS data:

<?xml version="1.0" encoding="UTF-8" ?>
<rss version="2.0">

<channel>
  <title>菜鸟教程首页</title>
  <link>http://www.runoob.com</link>
  <description>免费编程教程</description>
  <item>
    <title>RSS 教程</title>
    <link>http://www.runoob.com/rss</link>
    <description>菜鸟教程 Rss 教程</description>
  </item>
  <item>
    <title>XML 教程</title>
    <link>http://www.runoob.com/xml</link>
    <description>菜鸟教程 XML 教程</description>
  </item>
</channel>

</rss>

I saw many RSS sources, only have one channel, I am not sure whether the standard is just one channel of a RSS source.

Answer 1

According to this RSS 2.0 specification:

Subordinate to the <rss> element is a single <channel> element, which contains information about the channel (metadata) and its contents.

I cannot find a formal specification of RSS 1.0 or 0.9x that define how many channel elements a feed may contain.