+@cindex spam-stat, spam filtering
+@cindex spam-stat
+@cindex spam
+
+@xref{Filtering Spam Using Statistics with spam-stat}.
+
+@defvar spam-use-stat
+
+Enable this variable if you want @code{spam-split} to use
+spam-stat.el, an Emacs Lisp statistical analyzer.
+
+@end defvar
+
+@defvar gnus-group-spam-exit-processor-stat
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the spam-marked
+articles will be added to the spam-stat database of spam messages.
+@end defvar
+
+@defvar gnus-group-ham-exit-processor-stat
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the ham-marked
+articles in @emph{ham} groups will be added to the spam-stat database
+of non-spam messages. Note that this ham processor has no effect in
+@emph{spam} or @emph{unclassified} groups.
+@end defvar
+
+This enables spam.el to cooperate with spam-stat.el. spam-stat.el
+provides an internal (Lisp-only) spam database, which unlike ifile or
+Bogofilter does not require external programs. A spam and a ham
+processor, and the @code{spam-use-stat} variable for @code{spam-split}
+are provided.
+
+@node Extending the spam elisp package
+@subsubsection Extending the spam elisp package
+@cindex spam filtering
+@cindex spam elisp package, extending
+@cindex extending the spam elisp package