+With the
+.B \-a
+option,
+the argument list consists of new bad sectors to be added to an existing
+list.
+The new sectors are sorted into the list,
+which must have been in order.
+Replacement sectors are moved to accommodate the additions;
+the new replacement sectors are cleared.
+The entire process is described as it happens in gory detail if
+.B \-v
+(verbose) is given.
+The
+.B \-c
+option forces an attempt to copy the old sector to the replacement,
+and may be useful when replacing an unreliable sector.
+.PP
+If the disk is an RP06, RM03, RM05, Fujitsu Eagle,
+or SMD disk on a Massbus, the
+.B \-f
+option may be used to mark the new bad sectors as ``bad''
+by reformatting them as unusable sectors.
+This option is required unless the sectors have already been marked bad,
+or the system will not be notified that it should use the replacement sector.
+This option may be used while running multiuser; it is no longer necessary
+to perform format operations while running single-user.
+.PP
+It is no longer necessary to reboot to allow the kernel
+to reread the bad-sector table from the drive.