+present in DIR1 and not in DIR2. The and: prefix is assumed by default
+and necessary only if you have a directory name starting with `not:'.
+
+This command compares files by first comparing their sizes, hence goes
+reasonably fast.
+
+When looking for identical files, \fBfinddup\fP associates by default
+a group ID to every content, and prints it along the file names. Use
+the \fB-g\fP to switch it off.
+
+Note that
+.B finddup DIR
+is the same as
+.B finddup -i DIR DIR