You’d normally do all category maintenance from the category buffer.
When you enter it for the first time (with the J c command from
the group buffer), you’ll only see the default
category.
The following commands are available in this buffer:
Return to the group buffer (gnus-category-exit
).
Use a customization buffer to set all of the selected category’s
parameters at one time (gnus-category-customize-category
).
Kill the current category (gnus-category-kill
).
Copy the current category (gnus-category-copy
).
Add a new category (gnus-category-add
).
Edit the predicate of the current category
(gnus-category-edit-predicate
).
Edit the list of groups belonging to the current category
(gnus-category-edit-groups
).
Edit the download score rule of the current category
(gnus-category-edit-score
).
List all the categories (gnus-category-list
).