parameters will be scanned to generate the output split.
@var{no-crosspost} can be used to disable cross-posting; in this case, a
single @code{|} split will be output. @var{catch-all} is the fall back
-fancy split, used like @var{gnus-group-split-default-catch-all-group}.
+fancy split, used like @code{gnus-group-split-default-catch-all-group}.
If @var{catch-all} is @code{nil}, or if @var{split-regexp} matches the
empty string in any selected group, no catch-all split will be issued.
Otherwise, if some group has @var{split-spec} set to @code{catch-all},