Bob's solution will mean you will have to open the file to check that value.
If you will always be on systems that use NTFS, there is also Alternate Data
Stream. You can attached various data to files and it follows the file in a
not readily visible way.
I would not necessarily recommend using this method, but it's available, if
your Admin has not disabled it somehow. Make sure the you understand the
potential hazards.
http://www.personalinformationorgani...download/ntfs/

If using CustomDocumentProperties, you gave each prop a suitably obscure
name, any user that changed it/them, would be just guessing, determined to
cause trouble. Unfortunately, your code would have no way to know.

NickHK

"rahul" ...
My requirement is to uniquely identify any excel workbook across the
network,
which leads me to a requirement of tagging the document.

Possible solutions a-
1. using filename (not useful, since it can be changed)
2. using path (not useful, since file could be copied or moved)
3. using documentProperties (This solves my prob to a large extent, first
it
is persistent and associated with the workbook. The only problem is that
users could see the DocumentProperty in custom tab and change the value.)

Is there any way to hide the Documentproperty or another feasible way to
tag
an excel workbook.

Thanks,
Rahul