> Uwe Brauer <oub@mat.ucm.es> writes:

   > I'm not entirely sure what you're asking, but you have two options here:
   > set a global gnus-summary-line-format variable, that applies to all
   > groups, and also set a per-group (ie "group local") summary line that
   > only applies to that one group, and overrides the global value.

   > In the customization "screenshots" above, the top entry is specific to
   > one group. The second is the value that applies to all groups.

   > If that doesn't clear things up, you might need to rephrase your
   > question!

Ok, I was mistaken. I want  gnus-summary-line-format to be different for
my mail and the newsgroup.

That is why I use topic groups, so all my mail is organized like
    [ Mail 809073 ] 
*          0: nnimap+gmail:[Gmail]/Starred 
*          0: UCM-Flags-Starred 
      [ Imap_UCM_Gmail 809073 ] 
*            0: nnimap+UCMgmail:INBOX 
*            0: nnimap+UCMgmail:Maria 
*            0: nnimap+UCMgmail:MBOX 

Etc etc.

So when I customize the gnus-summary-line-format variable in
[ Mail 809073 ]
all the subgroups have the same line format.

However the registry does not work that is I set
Variables:
            Set variables local to the group you are entering. More
INS DEL Variable: gnus-summary-line-format
            Value: 
"[%uM]%U%R%z%I%N %(%[ %-10,10uB%]%) %-10,10~(form (rfc2047-decode-string (gnus-extra-header 'To)))@  [%-25,25s%] %D %k %L   \n"
INS

Note the []

then the messages after restart are displayed such as
[]O  36485 [  Uwe Braue] Uwe Brauer  [courier                  ] Mon, 20 Feb 2017 23:04:28 +0000 9k 21   


But when I want to add a registry label I obtain that error: