title: What is meaning of "xmlns:v=urn:schemas-microsoft-com" in HTML5
body: <p>I happened to find the sentence "xmlns:v=urn:schemas-microsoft-com" as title described</p>
  
  <p>Here is source roughly.</p>
  
  <pre><code>&lt;!--[if gt IE 8]&gt;&lt;!DOCTYPE html&gt;&lt;!--&lt;![endif]--&gt;
  &lt;!DOCTYPE html&gt;&lt;!--&lt;![endif]--&gt;
  &lt;html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office"&gt;&lt;br&gt;
      &lt;head&gt;
          &lt;meta http-equiv="X-UA-Compatible" content="IE=Edge"&gt;
          &lt;meta name="viewport" content="user-scalable=0,target-densitydpi=device-dpi"&gt;
          ...
      &lt;/head&gt;
      &lt;body&gt;
          ...
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>As I know xmlns is schema, so to speak metadata.
  If some element is available in body section, the metadata of this element exist in "schemas.microsft.com"</p>
  
  <p>If I develop a html page using "microsoft" schema,
  all elements used in body section will be referernced by "microsoft"
  Or, If I use other schema, examply "google" (I don't know whether this really exist)
  all element goes same too.</p>
  
  <p>Here is my question
  First,
  If I use table tag that exist in "microsoft" and "google" schema together
  Will chrome browser interpret context differently?
  so comes differnt view?</p>
  
  <p>Second,
  If xmlns is omitted
  what kind of schema will be used default?</p>