Publicly-Owned Private Spaces (or privatized public spaces) are places that are owned by the public, but have been privatized. They are the opposite of Privately-Owned Public Open Spaces. Examples are sections of sidewalk that have been closed off for exclusive use by a restaurant, or public stairs or pathways that have been fenced off to prevent access by the public.
To keep things clear, this is not meant to include places like courthouses, jails, fire stations, or other government buildings which are owned by the public, but the public is not given free access to.
Note that parklets are sometimes mistaken as publicly-owned private spaces, but by definition parklets in Oakland are public spaces, even if they are in front of a particular business which maintains them.