400 Bad Reques. Unrecognized element 'form'. Characters > < in Record Feed

[nakvic]

How to post a record to a gdocs spreadsheet with the filed that
contains characters like < > (i.e. &lt; &gt;).
A following post fails with "Bad Request. Content: [Line 1, Column
797, element gsx:note] Unrecognized element &#39;form&#39;".

  <entry gd:etag='"AxQDSXxjfyp7ImA0ChJVSBI."'>
    <id>https://spreadsheets.google.com/feeds/list/key/worksheetId/
private/full/rowId</id>
    <updated>2006-11-17T18:23:45.173Z</updated>
    <category scheme="http://schemas.google.com/spreadsheets/2006";
      term="http://schemas.google.com/spreadsheets/2006#list"/>

    .....

    <gsx:fieldname>Content <form> </gsx:fieldname>
  </entry>

I've tried whatever possible to escape <>. Nothing works.

How to post the symbols like these?

Regards,
Victor