I was thinking about the
or later part that is often used in licensing
software. When reading https://www.gnu.org/licenses/gpl-3.0.html, I've found
The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
However, nowhere in the text of the license is specified what is "The Free Software Foundation". The wording would be satisfied if I registered entity called "The Free Software Foundation" in Uruguay or somewhere and released something called GPLv4.
Would that actually be legal? Reading the text of the license, it should be enough, but since I have no legal background I'm not sure.