+@node Registry Article Refer Method
+@subsection Fetching by @code{Message-ID} Using the Registry
+
+The registry knows how to map each @code{Message-ID} to the group it's
+in. This can be leveraged to enhance the ``article refer method'',
+the thing that tells Gnus how to look up an article given its
+Message-ID (@pxref{Finding the Parent}).
+
+@vindex nnregistry
+@vindex gnus-refer-article-method
+
+The @code{nnregistry} refer method does exactly that. It has the
+advantage that an article may be found regardless of the group it's
+in---provided its @code{Message-ID} is known to the registry. It can
+be enabled by augmenting the start-up file with something along these
+lines:
+
+@example
+;; Keep enough entries to have a good hit rate when referring to an
+;; article using the registry. Use long group names so that Gnus
+;; knows where the article is.
+(setq gnus-registry-max-entries 2500
+ gnus-registry-use-long-group-names t)
+
+(gnus-registry-initialize)
+
+(setq gnus-refer-article-method
+ '(current
+ (nnregistry)
+ (nnweb "gmane" (nnweb-type gmane))))
+@end example
+
+The example above instructs Gnus to first look up the article in the
+current group, or, alternatively, using the registry, and finally, if
+all else fails, using Gmane.
+