What do browsesr use to auto suggest values in web forms?

If I come back to a web site after having filled in a form previously, the browser remembers my username (for example). I'm not talking about cookies remembering user names and passwords, but the way a browser will suggest a v开发者_JAVA技巧alue for a previously submitted field.

What controls this behaviour?

My issue at the moment is that I have login forms on several small apps all running under the one domain. (eg www.example.com/app1/login/ and www.example.com/app2/login/). If I use my user name for app1, then go over to app2 where I use a different username, it only ever auto suggests my app1 user name.

How can I change this behaviour? Do browsers use the fields ID to help remember this stuff? If I change the ID of the fields in the login form, will they auto suggest the correct values in future?

This has been asked before, and there is no way to prevent it other than shutting off suggestions completely (which can only be done by the client). Browsers remember them by base domain name, period, that's just how they work. Changing the names or IDs may or may not work depending on the browser and version.