Collect two values:
1. What do you want to be called? e.g. if we send you an email we'll say Hello {name}
2. What is your legally recognised name i.e. what's on your passport and official documents.
#2 is only relevant in some domains, in many cases #1 alone is sufficient.
1) People can have multiple passports with different names.
2) a single passport can contain multiple names for the same person.
AFAIK, the MRZ and chip don’t support alias fields?
3. A string that will never be displayed, but will result in proper sorting. It's not simply a concatenation of all name parts, though. Omitting spaces and punctuation is also critical for a nice sort, so that apostrophes and the like don't shunt things to the top or bottom. But don't just filter to Latin letters, keep all [0] letters!
When my last company did phone numbers we just let it be free text…
I've even run into trouble occasionally as a Western person with fairly normal first and last but no middle name. More than once I've been confronted with online forms that require a middle name (not for many years though, thankfully).
Good times.
There is an ISO standard for phone numbers, actually. There are even libraries to parse phone numbers into the format. That being said, for “non machine readable” phone numbers (say for a contacts app) some say you should keep it free text because people plug all kinds of shit into the field and if you aren’t using it to send messages/voice/whatever just let the user do whatever…
The problem arises when the order is reversed (e.g Vietnamese), or when there's only one name and the form requires at least two names. And probably for other name formats saying around the world that I'm not aware of.
First: Miquel Middle: empty Last: Martí i Pol
The problem is for names that don't work in that format.