This is actually a very resourceful tool that you probably won't utilize the results of 98% of the time, but that other 2%, you will wish you did.
Near the bottom of the box, there is a text field called 'comment:'. If you type a short but quick note about what you did before that particular 'save to central' operation that comment is saved with the file. If you ever needed to roll back the file to a previous version (which maybe happens once a project) because of some error or something else in the file, you can easily (by looking at the history of the file) see what you, or someone else on your team did and will know immediately to which point you will need to roll back the file.
