The content summary contains the owner, who added the content by drag-and-drop. The owner: query results in the content added by the specified user.
“me” may be used as a username for the current user. So if this query is used in a panel, every user sees content added by themselves.
You can query the documents that a specific user and group has seen. These queries can also be used for classification. For example, if a certain group sees a document, you can say it is confidential.