P: Ability to lock photos to prevent further editing

I'm a relatively newbie to Lightroom and I think it is fantastic.

It does occur to me that pros who have been using Lightroom for a while understand all the issues about selections, settings, copying, pasting, synchronising etc etc.

Like many things in life the people who do things almost as second nature forget what it was like to be a beginner.

The one thing that has surprised me about lightroom is that I cannot find a way of indicating "I am happy with this - I just want to lock it to ensure I don't damage, amend or delete it" through my own incompetence.