There are a couple of db_errors that are at odds with the current Euro Aristo naming standards. One in particular that is being discussed at the moment is db_error_733 Prefix in Preferred Name, and there needs to be some more input to reach some agreement about what to do about this.
The EuroAristo naming standard is that the preferred name includes the number attached to a ruler. See the profile below for Edward II where Edward is his first name and Edward II is the preferred name, but that then comes up as an error.
Although I admit that having the numeral in the preferred name is a bit of a problem because a search for Edward Plantagenet, won't easily differentiate between Edward II, his father Edward I or his son Edward III. However I'm not sure where else you would put the numeral. It could go in the Proper First Name field, but that is usually for the first name at birth, and except for a few rare occasions most rulers didn't become so at birth.
There is a suggestion that it goes in the suffix field but in the case of Edward II that would end up looking like this
Edward "King of England, Prince of Wales, of Caernarfon" of England formerly Plantagenet II
The other option is that there is no change to the EuroAristo naming standards in relation to preferred name, and the error is discounted or marked as false in regards to rulers (of all nationalities)
Perhaps there are other suggestions?