blank=type
              Blank  a  CD-RW  and  exit or blank a CD-RW before writing. The
              blanking type may be one of:

              help        Display a list of possible blanking types.

              all         Blank the entire disk. This may take a long time.

              fast        Minimally blank the disk. This results  in  erasing
                          the PMA, the TOC and the pregap.

              track       Blank a track.

              unreserve   Unreserve a reserved track.

              trtail      Blank the tail of a track.

              unclose     Unclose last session.

              session     Blank the last session.
       Not  all drives support all blanking types. It may be necessary to use
       blank=all if a drive reports a specified command as being invalid.  If
       used  together  with the -force flag, this option may be used to blank
       CD-RW disks that otherwise cannot be blanked. Note that you  may  need
       to  specify  blank=all because some drives will not continue with cer-
       tain types of bad CD-RW disks. Note also that cdrecord does it’s  best
       if  the  -force  flag  is  used  but it finally depends on the drive’s
       firmware whether the blanking operation will succeed or not.