What will occur if the .DocumentRevisions-V100 folder is deleted?
Just because one cannot see something's purpose or value doesn't mean there isn't one!

If you delete the /.DocumentRevisions-V100 directory it will break the Document Revisions feature in OS X until you reboot. At which point the /.DocumentRevisions-V100 directory is recreated.

Somewhere along the way the Document Revisions feature changed, i.e. it's not the same in OS X 10.11 as it is in OS X 10.8, e.g. in OS X 10.8 in TextEdit I can click the down arrow to the right of the filename in the title bar of the document and select Browse All Versions..., and it opens the Time Machine interface when I can view the various versions of the document that are stored within the /.DocumentRevisions-V100 directory. This is not the case in OS X 10.11. I'm not sure when this feature changed to have less importance then it used to have in e.g. OS X 10.8.

In OS X 10.11, if you delete the /.DocumentRevisions-V100 directory, without rebooting, and create a new document in TextEdit and save it, then reopen and edit it, then click the close button... you'll get the a dialog box, "Do you want to save the changes made to the document You can revert to undo the changes since you last opened the document." and if you click the Revert Changes button, it errors out with "The operation couldn’t be completed. No such file or directory" until you reboot.

Note: This assumes you have Ask to keep changes when closing documents checked in General under System Preferences.



If you want to clean up what's in the /.DocumentRevisions-V100 directory, then close all applications except for Terminal, and use the following command:

sudo rm -rf /.DocumentRevisions-V100


Then reboot.

NOTE: Make sure you have a proper Time Machine Backup and be very careful using the above command, make sure it is properly formed and there is no space between / and .DocumentRevisions-V100! You have been warned!

It would actually be more safe to do it in two steps, e.g.:

cd /
sudo rm -rf .DocumentRevisions-V100