INPUT Type=image In IE

I noticed that the image input type does not show up in the elements
array (IE 6.0).

<FORM name=myForm>
<INPUT name=rads id=check1 type=radio value=val1>
<INPUT name=rads id=check2 type=radio value=val2 checked>
<INPUT name=rads id=check3 type=radio value=val3>
<INPUT name=rads id=check4 type=radio value=val4>

<INPUT name=imgIn type=image src=web.gif>
<INPUT type=button name=somethin>
</FORM>

If I have this HTML code, the myForm.elements.length is 5, instead of
the expected 6. You can click on the image in this case, and it acts
like a submit button... proof that the broser recognizes it as part of
the form.

So, if I call myForm.elements[4], I get the button, not the image.

It seems goofy to me, and I cannot find any documentation that explains
why this is.

Of course, I can get access to the object in many other ways... I am
just curious if the is an IE bug.