What does it mean when the "user-details" block of a "user card" of an answer has a name but no link, no reputation, and no badges?
For example: on this answer by "Peter" on Mar 8 '09 at 14:26
In general it means that account either:
Since this was not a migrated question, only #1 applies here, so we can conclude the account has been deleted since the answer was posted.
In this case it is a deleted account.
It can also happen when a question is migrated — any posters that do not have accounts on the new site will appear in the same format.