I just got a DR-05 and I can't figure out what the hold switch on the side does. It seems to have no obvious effect on either recording or playback, and the manual says virtually nothing about it. I expected it to act like a pause or mute but it does neither. Maybe it holds the level of the automatic gain control? Does it have to be enabled by a menu entry?
On the DR-07, the HOLD switch disables the control buttons. It is useful to ensure that a recorder stowed in a bag or pocket is not turned on accidentally, thus accidentally running down the batteries. It also is useful to ensure that a recording or playback is not interrupted by an accidental press of a button, or by the press of a too-curious observer. The DR-40 also has a HOLD button.
OK, That's handy. It would have taken me a while to figure it out though. I am new to modern audio gear.