When you have a form with a fieldname 'x' and/or 'y' and you put an image as submit button, instead of the usual submit button, PHP will add random numbers to it:

Small source code to reproduce this error:
-------------------------------------------------------
<?php
if(!$x && !$y && !$z) { $x="undefined"; $y=$x; $z=$x; }
print "X is: <strong>$x</strong><br>\n";
print "Y is: <strong>$y</strong><br>\n";
print "Z is: <strong>$z</strong><br>\n";
?>
<hr>
<form action="<?php echo $PHP_SELF;?>">
X: <input type="text" name="x" size="3"><br>
Y: <input type="text" name="y" size="3"><br>
Z: <input type="text" name="z" size="3"><br>
<br>
<input type="submit" value="search"><br>
<input type="image" src="search.jpg" alt="search">
</form>
-------------------------------------------------------

As you can see, the value's will be the same when you hit the original submit button, but the values will differ when you hit the image.

I have created a similar form in Perl (CGI), but that does not seem to have the same akward result.

Kind Regard,

-- 
M. J. Blom
menno@b10m.net