Where is "Lock Timeline?"

I noticed that there's a "Lock Timeline" command listed in Keyboard Customization under Panels->Media Pool->Timelines, but I don't see it anywhere in the interface, no matter which page I'm in or whether I'm context-clicking a currently active or inactive timeline.

Is this an old feature that disappeared with the introduction of "Disable Timelines" in R17, but hasn't yet been purged from the Keyboard Customization list? Or is it a missing menu item? Or am I just looking in the wrong place?

I tried assigning a shortcut and using that, but it doesn't appear to do anything.

I also searched the forum, but only found a feature request from 2018.

With collaboration enabled (Timeline > Enable Collaboration), the Timeline's contextual menu in the Media Pool provides the following preference based on current state:
Timelines > Unlock/Lock Timeline

Resolve Manual August 2020 | Page 3572 | Chapter 178 | Collaborative Workflow

With collaboration enabled...

Ah, so that sounds like "lock" in this case means "prevent anyone else from making an update while I work on this timeline", as opposed to "prevent any changes to the timeline, period".

With collaboration enabled (Timeline > Enable Collaboration), the Timeline's contextual menu in the Media Pool provides the following preference based on current state

Drat. Forgot about Collaboration, and should've thought to search the manual. Thanks, though!

With collaboration enabled...

Ah, so that sounds like "lock" in this case means "prevent anyone else from making an update while I work on this timeline", as opposed to "prevent any changes to the timeline, period".

It's been almost two years since I used the collaborative workflow, I could've sworn that it automatically locked other collaborators out without you having to check any boxes... no matter. I was hoping it was more, as you said, "prevent any changes to the timeline, period."

When I version, I shift-click the lock in the headers to keep Future Me from making any dumb mistakes. But it's a little hack-y, and I was hoping for a more global control to do basically the same thing, but would better communicate the message to other editors: "Don't Touch."