(edit: it's archived: http://archive.is/H9EYE )
[†] I can see how this replaces ad revenue at all, so I assume it is an attempt to make running an ad blocker seem like an inconvenience rather than a benefit.
May read it as: CREATE TABLE thing (T_ID integer, C_ID integer)
Is this an industry term or are you just using it here to emphasize the difference?
EDIT: Agree with panda17, they're using it as "candidate keys which were not chosen as primary key."