When a user submits a request from a web form outside of ILLiad (such as through OpenURL or another system), ILLiad will first display a login screen. Once the user has logged in to their account, ILLiad will automatically place the request. In order to carry OpenURL or EAD information through the login or registration process to a request form, the FORMSTATE tag must be present on all web pages that are displayed before logging on to the system.
Please see full the document- https://support.atlas-sys.com/hc/en-...-FORMSTATE-Tag