title: pdftk watermark above page
body: <p>I'm using pdftk to fill a pdf form with an xfdf file.
  Once this is done I use another pdf (containing a big red "SPECIMEN") as a watermark with the following command :</p>
  
  <pre><code>shell_exec(SOURCE_PDF stamp WATERMARK_PDF output - flatten);
  </code></pre>
  
  <p>The result is good, all the pages have the watermark.
  However, the dynamic content in the form fields is displayed above the specimen.</p>
  
  <p>I find nothing about this problem in the documentation or even stackoverflow.</p>
  
  <p>Do you know if I can force the watermark to be on the top ?</p>
  
  <p>Thanks</p>