/For=ForVolumeSpec /Shadow=ShadowId|/Set=ShadowSetId - Displays existing shadow copies on the system. Without any options, ...

%1 %2 [/For=ForVolumeSpec] [/Shadow=ShadowId|/Set=ShadowSetId]
    - Displays existing shadow copies on the system.  Without any options, 
    all shadow copies on the system are displayed ordered by shadow copy set.  
    Combinations of options can be used to refine the list operation.  
    - The Shadow Copy ID can be obtained by using the List Shadows command.
    When entering a Shadow ID, it must be in 
    the following format:
       {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX} 
    where the X's are hexadecimal characters.  

    Example Usage:  vssadmin List Shadows 
                             /Shadow={c5946237-af12-3f23-af80-51aadb3b20d5}