What is Nell's real name??

[satsucake]

I saw many alternate spellings for Nell's name.. I was wondering if anyone could shed some light on which one is "official"? These are some of the ones I've seen:

Neliel Tu Oderschvank
Neliel Tu Oderschwank
Nelliel Tu Oderschvank
Nelliel Tu Oderschwank

Any comment from you guys will be greatly appreciated. Thanks so much!