It could be either user type. Our scenario is this:

1. We will have users go thru a Checkbox survey. Those users could be registered or anonymous.

2. After the survey, we want to pass the user to a Flash application where we gather other data.

I was looking for one unique ID that identifies the respondent, regardless of type. Then I can easily relate the Checkbox data and my other application data, based on this unique respondent ID. But this doesn't look possible since you use different ID's for different kinds of users?