Having such an "Other" value does not prevent from considering that the enum is open-ended, and it simplifies a lot all the code that has to deal with potentially invalid or unknown values (no need for a validity flag or null).
That's probably why in DIS (Distributed Interactive Simulation) standard, which defines many enums, all start with OTHER, which has the value zero.
In STANAGs (NATO standards), the value zero is used for NO_STATEMENT, which can also be used when the actual value is in the enum but you can't or don't need to indicate it.
I remember an "architecture astronaut" who claimed that NO_STATEMENT was not a domain value, and removed it from all the enums in its application. That did not last long.
That also reminds me of Philippe Khan (Bordland) having in some presentation the ellipse extend the circle, to add a radius. A scientist said he would do the other way around, and Khan replied: "This is exactly the difference between research and industry".