<?php
if ($_POST) {echo "Post variable set!";}
else {echo "Post variable NOT set!";}
?>
<HR>
<FORM ACTION="<?php echo $_SERVER['PHP_SELF']; ?>" METHOD="post" TITLE="cool">
<INPUT TYPE="checkbox" VALUE="cool" NAME="Checkbox" CHECKED>
<INPUT TYPE="submit" VALUE="SUBMIT_ME" NAME="Form_submit">
</FORM>