exclude open file in backup with rsync

[IMCC]

hi,
   I am working on Backup appliction.
   So I am understanding  rsync_2.6.6.

   I have to take a backup of files on a drive But 
   I  have to exclude those file in a drive which are open. 

   I want to know  whether rsync exclude open files
   while taking backup ? .
    
   and how rsync identify a file  open or not.
   what test on a file rsync does.

						  sunil
						 SPSOFT