Gurus will come here soon, but I guess using worksets is the key. Not very familiar with them, up to you gurus....

a brief word, when creating workset for the first time, default workset contains grids and levels.

I dont think there is any way to absolutely lock elements. When I am faced with a similar condition where I dont want people touching things. I use Design Options. You can find info on this is the help.

Basically your grids will be an design option and they will be unselectable unless someone activated the option they are under (takes several clicks and a good understanding of design options)

Hope this helps. Others may have a better way of doing this, but it works for me.

Impressed with quick response

Design options is a very good idea. It means the grids won't be selectable, which is exactly what I'm after. Thanks and I'll definately use this forum again if answers are this quick.
Cheers
David.

Glad you found a solution. We look forward to more questions.

Cheers

We avoid using design options for locking elements. We we exchange models with our consultants we make sure there are no active design options, so there is no question about what is in the project.

I have heard of a method where you place all elements in a workset that is owned by a non existing member. If you need to edit something you change your username in revit and edit the file.

I have never used this method myself so I don't know if this is fool/monkey-proof. But you could test it.

there are 2 ways to lock it down using worksets. 1 - you take ownership of the workset and don't relinquish when you exit Revit. 2 - change your username to admin (or anything that isn't someone else's username) open a new local file, take ownership of the workset there, save and don't relinquish. Then change your username back to you and create a new local for you. Option 2 is more fool-proof than 1 (if your users aren't knowlegeable enough when they get the warning "can't edit the element until admin relinquishes") because in Option 1, you can accidentally bump/delete things.

You just have to make sure that in your SWC dialog box that the User-Created Worksets is NOT checked. This will allow you (or admin) to keep control of those worksets. Then once you synch and go to close, it will ask you if you want to Relinquish elements and worksets or Keep ownership of elements and worksets - always choose the second one because otherwise the worksets become avaliable to everyone again.

Ok, I'm not all too familiair with worksets, but doesn't this give the problem that all other worksets you are working on also don't get Relinquished? I always tell my customers to ALWAYS relinquish when closing down or there will be trouble (when they get sick, go on vacation, hit a tree on the way home, etc).
Can you specify which worksets you wish to Relinquish?

the only time I ever check out an entire workset is for locking it down. Or if there is a big change that needs to happen, and usually I tell everyone else to get out of the model for a 1/2 hour. When you SWC you have the option to relinquish Borrowed Elements separate from user-created Worksets. So, if you only "own" the grids workset or the Linked Structural Model Workset (because each of my consultants links goes on it's own workset) then you can relinquish the elements you borrowed but not the ability to change anything. Just because I have the workset fully checked out doesn't mean you can't put something on it. It just means you can't change anything once it's there. And if you check out a workset that you will wish to relinquish before you leave for the day, just go to your workset dialog box and change it back to No in the Editable column. Then you no longer are the owner and you are now only borrowing elements, which you relinquish when you SWC