"There can be other combinations"--other combinations of Neapolitan? Isn't it always chocolate, strawberry, and vanilla?? --LMS (lover of Neapolitan, but not therefore a Latin lover)
Neapolitan doesn't have to be those three, according to http://www.allrecipes.com/encyc/terms/N/7588.asp (I assume this is true because it says so) and http://www.probertencyclopaedia.com/Q4.HTM
This site says it is #5, though: http://www.makeicecream.com/15mospopicec.html ...on some other sites I found, it was #3, after vanilla (#1) and chocolate (#2): http://www.bayarea.com/entertainment/guide/summer/docs/icecream5.html