Roman Numerals - Birth Date?

Question

Looking for the date 18/ 12 (December)/ 2003. I think i may have it but just wanna check. Figured where better to ask than Answers, where i can use the wealth of knowledge from people around the globe. Many thanks

Answer 1

Australian style:  XVIII . XII . MMIII

American style: XII . XVIII . MMIII

(This would probably be expressed, in Latin. as XVIII day of December,  MMIII.)

Answer 2

MMIII is 2003 but I don't know how you'd represent the days and months. XIIX/XII/MMIII?