protected link
For when some or all of a posts are made private except to a certain subset of users by an artist. This can include limiting the view of a picture to certain sizes only, to flat-out denying access to the picture at all. Also, although the images are blocked, this is not considered to be a bad id.
This can be detected if a post link redirects to the user's homepage with the URL addon "protected_redirect=true".
Example: https://twitter.com/mup_nim?protected_redirect=true
