Canceling and Superseding The Summary Buffer Limiting
There are several marks you can set on an article.
You have marks that decide the readedness (whoo, neato-keano neologism ohoy!) of the article. Alphabetic marks generally mean read, while non-alphabetic characters generally mean unread.
In addition, you also have marks that do not affect readedness.
There's a plethora of commands for manipulating these marks:Canceling and Superseding The Summary Buffer Limiting