So I'm trying to figure out why the following is evaluating as true, I always thought if the `checked` attribute was omitted, then it wouldn't evaluate as checked. I've double checked the below to make sure the state isn't changing due to some JS. Also verified on Chrome, Safari and Firefox and all evaluate this to a checkbox being checked. Any ideas why?

```
<input type="checkbox" name="shipping[same_as_billing]" id="shipping:same_as_billing" value="1" onclick="shipping.setSameAsBilling(this.checked);">

```