gnus-newsgroup-variables

gnus-newsgroup-variables is a variable defined in `gnus-sum.el'.
Its value is

nil

Documentation:
A list of variables that have separate values in different newsgroups.
A list of newsgroup (summary buffer) local variables, or cons of
variables and their default expressions to be evalled (when the default
values are not nil), that should be made global while the summary buffer
is active.

Note: The default expressions will be evaluated (using function `eval')
before assignment to the local variable rather than just assigned to it.
If the default expression is the symbol `global', that symbol will not
be evaluated but the global value of the local variable will be used
instead.

These variables can be used to set variables in the group parameters
while still allowing them to affect operations done in other buffers.
For example:

(setq gnus-newsgroup-variables
'(message-use-followup-to
(gnus-visible-headers .
"^From:\\|^Newsgroups:\\|^Subject:\\|^Date:\\|^To:")))