-Set output format. Default is I<dump>, consisting of an alphabetical
-list of newsgroups, each on a new line, followed by the number of
-postings in that month. This default format can't be used with time
-periods of more than one month.
+Set output format. Default is I<pretty>, which will print a header for
+each new month, followed by an alphabetical list of newsgroups, each
+on a new line, followed by the number of postings in that month.
+B<groupstats> will try to align newsgroup names and posting counts.
+Usage of B<-b> will force this format; it cannot be used together with
+B<-f>.
+
+I<dump> format is used to create an easily parsable output consisting
+of an alphabetical list of newsgroups, each on a new line, followed by
+the number of postings in that month, without any alignment. This
+default format can't be used with time periods of more than one month.
+Usage of B<-f> will force this format.