> It means: "TTP certifies that the user presenting identity X is indeed a user known to me, and is an acceptable user for the purposes that Site asked about: n

> It means: "TTP certifies that the user presenting identity X is indeed a user known to me, and is an acceptable user for the purposes that Site asked about: not a bot, not a spammer". How does the TTP know that the user isn't a spammer? Is there a backchannel for reidentifying users in case of abuse allegations? Does the TTP just refuse to issue credentials on behalf of the same user very frequently?