Hiding Headers
==============

   The top section of each article is the "head".  (The rest is the
"body", but you may have guessed that already.)

   There is a lot of useful information in the head: the name of the
person who wrote the article, the date it was written and the subject
of the article.  That's well and nice, but there's also lots of
information most people do not want to see--what systems the article
has passed through before reaching you, the `Message-ID', the
`References', etc. ad nauseum--and you'll probably want to get rid of
some of those lines.  If you want to keep all those lines in the
article buffer, you can set `gnus-show-all-headers' to `t'.

   Gnus provides you with two variables for sifting headers:

`gnus-visible-headers'
     If this variable is non-`nil', it should be a regular expression
     that says what headers you wish to keep in the article buffer.  All
     headers that do not match this variable will be hidden.

     For instance, if you only want to see the name of the person who
     wrote the article and the subject, you'd say:

          (setq gnus-visible-headers "^From:\\|^Subject:")

     This variable can also be a list of regexps to match headers that
     are to remain visible.

`gnus-ignored-headers'
     This variable is the reverse of `gnus-visible-headers'.  If this
     variable is set (and `gnus-visible-headers' is `nil'), it should
     be a regular expression that matches all lines that you want to
     hide.  All lines that do not match this variable will remain
     visible.

     For instance, if you just want to get rid of the `References' line
     and the `Xref' line, you might say:

          (setq gnus-ignored-headers "^References:\\|^Xref:")

     This variable can also be a list of regexps to match headers that
     are to be removed.

     Note that if `gnus-visible-headers' is non-`nil', this variable
     will have no effect.

   Gnus can also sort the headers for you.  (It does this by default.)
You can control the sorting by setting the `gnus-sorted-header-list'
variable.  It is a list of regular expressions that says in what order
the headers are to be displayed.

   For instance, if you want the name of the author of the article
first, and then the subject, you might say something like:

     (setq gnus-sorted-header-list '("^From:" "^Subject:"))

   Any headers that are to remain visible, but are not listed in this
variable, will be displayed in random order after all the headers that
are listed in this variable.

   You can hide further boring headers by entering
`gnus-article-hide-boring-headers' into `gnus-article-display-hook'.
What this function does depends on the `gnus-boring-article-headers'
variable.  It's a list, but this list doesn't actually contain header
names.  Instead is lists various "boring conditions" that Gnus can
check and remove from sight.

   These conditions are:
`empty'
     Remove all empty headers.

`newsgroups'
     Remove the `Newsgroups' header if it only contains the current
     group name.

`followup-to'
     Remove the `Followup-To' header if it is identical to the
     `Newsgroups' header.

`reply-to'
     Remove the `Reply-To' header if it lists the same address as the
     `From' header.

`date'
     Remove the `Date' header if the article is less than three days
     old.

   To include the four first elements, you could say something like;

     (setq gnus-boring-article-headers
           '(empty newsgroups followup-to reply-to))

   This is also the default value for this variable.