SIGMA DP1 - Manual (Page 85)

84
TO LOCK MULTIPLE FILES
1
Press the  button to open [ Playback Menu ].
2
Use the  button to select =Lock] and press the  button. 
3
Select [Lock all marked] or [Lock all] by using the button and press
the button.
4
To apply the settings, select [Yes] by using the  button and press the
button.

A  icon will appear in the upper-right corner of the file indicating that all
files are locked.

To dismiss Lock, select [No] and press the  button.
UNLOCKING MULTIPLE FILES
Please refer to the following for instruction on how to unlock all files.
1
Select [ Unlock all ] in step 3 and press the  button.
2
To apply the setting, select [Yes] by using the  button and press the
 button.
To dismiss Unlock, select [No] and press the  button.