INFO: Version en.xModule type:

Working copies

As soon as a file is opened for editing, a copy of the page is created, the so-called working copy. All changes are made in the working copy during editing; only when the page is saved are the new/changed contents saved in the original page and are then published directly.

As long as the file is in editor mode and the editor window is open, the working copy is retained. The file is then locked and cannot be edited in parallel by other editors.