  correcting VMS$COMMON backlinks? 
 The Question is:
 
Hello again, and thank you for the Wizard Pages!
 
Background
----------
Using the command:
  $ dump/head/bl=co=0 sys$sysdevice:[0,0]vms$common.dir
 
The file NAME as recorded in the file header is SYSCOMMON.DIR
The BACKLINK is (4,4,0). ANAL/DISK/REPAIR does
not correct the name in the file header. (And
of incidental note: DFU identifies the backlink
as being incorrect, and corrects the filename)
 
The net result is that a LIB$FID_TO_NAME of a file
underneath [vms$common] results in an unuseable
filename beginning with:
   dev:[SYSCOMMON
 
 
 
Questions
---------
Is this expected behavior, or is it actually incorrect?
 
How can I correct this problem in a supported way?
 
 
Thank You!
 
 
 The Answer is:
 
  This backlink oddity cropped up with image BACKUP restorations using
  specific versions of the OpenVMS BACKUP utility.  It is largely quite
  harmless, though it does cause certain utilities to present the wrong
  name when traversing using the backlinks.
 
  DFU works as well as any other tool for correcting the backlink.
 
  For this specific case, the following commands will correct the backlinks:
 
	$ SET DEFAULT SYS$SYSDEVICE:[000000]
	$ RENAME VMS$COMMON.DIR SYSCOMMON.DIR
	$ RENAME SYSCOMMON.DIR VMS$COMMON.DIR
 
  The first RENAME changes the entry to match the existing backlink. The
  second RENAME changes it back to the correct name. Since the entry now
  matches the backlink information in the header (which indicates that it
  is the "primary" entry), the header is updated to match the new entry.
 
