- BenAnswered on August 11, 2015 at 02:46 PM
Username and password are both not allowed.
While technically "username" is something that would not allow you to enter into some account, it might be used for social hacking and similar, but what it will do, is that it will cause you issues with your form/account.
Basically you should be OK using it, but at any point, your form can be removed, or your form and account suspended, depending on the circumstances around the form.
Taking all that into account, I would personally suggest to not use it on your forms.