Differentiating multiple forms on one site for autocomplete

Question

What's the logic behind browsers autocomplete - how do they differentiate between multiple forms on one site or even page? Let's assume a situation where you have an ecommerce-site with a login (user/pass) and gift-cards on checkout (giftcardnumber/pass). How do you tell a browser that these are not the same fields and must be stored separately?

Of course we could just disable autocomplete on the 2nd form, but that's not a pretty solution.

Is there a standard on autocompletion? Is the forms ID the key for storing it? Since Windows 10, the situation seems to be even more complicated, thanks to the cloud-sync feature, which syncs passwords and other form-values across browsers.

Thanks!

Answer 1

Here's a good answer that explains a little on how browser's determine autocomplete

Basically, browser's rely on the "name" attribute of an input and a lot of other contextual information (class/input type/label) to determine what fields can be autocompleted with what (type) of information.

Here's is a little more detail on the autofill html standard. https://html.spec.whatwg.org/multipage/forms.html#autofill