Read Articles
-------------
All the following marks mark articles as read.
`r'
These are articles that the user has marked as read with the `d'
command manually, more or less (`gnus-del-mark').
`R'
Articles that have actually been read (`gnus-read-mark').
`O'
Articles that were marked as read in previous sessions and are now
"old" (`gnus-ancient-mark').
`K'
Marked as killed (`gnus-killed-mark').
`X'
Marked as killed by kill files (`gnus-kill-file-mark').
`Y'
Marked as read by having too low a score (`gnus-low-score-mark').
`C'
Marked as read by a catchup (`gnus-catchup-mark').
`G'
Canceled article (`gnus-canceled-mark')
`F'
SOUPed article (`gnus-souped-mark'). Note:SOUP.
`Q'
Sparsely reffed article (`gnus-sparse-mark'). Note:Customizing
Threading.
`M'
Article marked as read by duplicate suppression
(`gnus-duplicated-mark'). Note:Duplicate Suppression.
All these marks just mean that the article is marked as read, really.
They are interpreted differently when doing adaptive scoring, though.
One more special mark, though:
`E'
Marked as expirable (`gnus-expirable-mark').
Marking articles as "expirable" (or have them marked as such
automatically) doesn't make much sense in normal groups--a user
doesn't control expiring of news articles, but in mail groups, for
instance, articles marked as "expirable" can be deleted by Gnus at
any time.