@al hart said:
The locked feature on groups and components is marked as SU 6. If it was added that recently, I wonder why they didn't invent some kind of owner/password scheme for it. (Of course, it they had, someone would have had to find a way to remove the password - e.g. save as DAE and reload.)
I just checked with SU5 - no locking feature. Though, the manual never reports anything less than SU6.
The Locking is like you'd use in Photoshop, Illustrator etc, as Jeff mentioned. Also in AutoCAD. It's not to prevent other people from ever from editing it. It's just a safety mechanism to protect you from yourself when you're being a bit zealous with the selection tool and eraser.
I use when I import CAD plans into SU to model from. I lock the imported plan while I model on top of it. That way I ensure that I don't confidentially move the plan around and mess things up.
Password protecting it would be going a bit far.
Locking is just something which forces you to be 100% conscious that you actually want to edit/delete an object.