Read Articles
-------------

   All the following marks mark articles as read.

`r'
     Articles that are marked as read.  They have a `r'
     (`gnus-del-mark') in the first column.  These are articles that the
     user has marked as read more or less manually.

`R'
     Articles that are actually read are marked with `R'
     (`gnus-read-mark').

`O'
     Articles that were marked as read in previous sessions are now
     "old" and marked with `O' (`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 a too low 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').

`Q'
     Sparsely reffed article (`gnus-sparse-mark').

   All these marks just mean that the article is marked as read, really.
They are interpreted differently by the adaptive scoring scheme,
however.

   One more special mark, though:

`E'
     You can also mark articles as "expirable" (or have them marked as
     such automatically).  That doesn't make much sense in normal
     groups, because a user does not control the expiring of news
     articles, but in mail groups, for instance, articles that are
     marked as "expirable" can be deleted by Gnus at any time.
     Expirable articles are marked with `E' (`gnus-expirable-mark').