Wikipedia
N-diaeresis
"N̈", or "n̈" (referred to as n-diaeresis or n-umlaut) is a grapheme from several minor extended Latin alphabets, the letter N with a diaeresis mark.
It occurs in the orthographies of Jacaltec (a Mayan dialect), Malagasy, and Cape Verdean Creole, in all three cases representing a velar .