Delete the automaticly added <body><head> tags

I have a small issue.

In my website I let php include some html files. They are html files without the <body></body> <head></head> tags. The main page of my site includes this files, and therefore don't need these tags. In my index.php file the are the necessary headers.

If I open a html-file (which can be included) in the SnippetMaster, the program added the following information.

Before the text:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Untitled Document</title>
</head>

After the text.

</head>
</body>

Is it possible to disable this, I'ld like to keep my site HTML valid.

Thanks in advance.