Smart Key - GNUS Newsreader ​

bash
If pressed within the Gnus newsgroups listing buffer:
  ACTION KEY
     (1) on a GNUS-GROUP line, that newsgroup is read;
     (2) if ‘gnus-topic-mode’ is active, and on a topic line, the topic is
         expanded or collapsed as needed;
     (3) to the left of any GNUS-GROUP line, within any of the
         whitespace, the current group is unsubscribed or resubscribed;
     (4) at the end of the GNUS-GROUP buffer after all lines, the
         number of waiting messages per group is updated.
bash
  ASSIST KEY
     (1) on a GNUS-GROUP line, that newsgroup is read;
     (2) if ‘gnus-topic-mode’ is active, and on a topic line, the topic is
         expanded or collapsed as needed;
     (3) to the left of any GNUS-GROUP line, within any of the
         whitespace, the user is prompted for a group name to subscribe
         or unsubscribe to;
     (4) at the end of the GNUS-GROUP buffer after all lines, the
         newsreader is quit.
bash
If pressed within a Gnus newsreader subject listing buffer:
  ACTION KEY
     (1) on a GNUS-SUBJECT line, that article is read, marked deleted,
         and scrolled forward;
     (2) at the end of the GNUS-SUBJECT buffer, the next undeleted
         article is read or the next group is entered.
bash
  ASSIST KEY
     (1) on a GNUS-SUBJECT line, that article is read and scrolled
         backward;
     (2) at the end of the GNUS-SUBJECT buffer, the group is exited and
         the user is returned to the group listing buffer.
bash
If pressed within a Gnus newsreader article buffer:
  ACTION KEY
     (1) on the first line or at the end of an article, the next unread
         message is displayed;
     (2) on the first line of an Info cross reference, the referent is
         displayed;
     (3) anywhere else, the window is scrolled up a windowful.
bash
  ASSIST KEY
     (1) on the first line or end of an article, the previous message is
         displayed;
     (2) on the first line of an Info cross reference, the referent is
         displayed;
     (3) anywhere else, the window is scrolled down a windowful.