When VSys is told to register someone into a project, it first checks to see if that person is banned from participation. It does this in two stages:
The first check is very quick and unambiguous - VSys will simply prevent you from registering this person under any circumstances, and this cannot be overridden without first marking the person as not banned.
The second is more complex. Does the person to be added have:
If any of these three are true, VSys will flag the person as being possibly banned. This won't prevent you from registering the person. Instead, VSys will prompt you to check to ensure that the person you're registering really is not banned. VSys does this to make sure that people who are banned and re-register again as a new person, either intentionally or accidentally, are less likely to get through your screening process.