I have a pixie cut, but it is slightly growing out.
My mom also currently has a pixie cut but her sides and back are buzzed short with clippers and on the nape area is made v shape and some small design.
But long back when mom had really long hair, she had got a undercut on her nape. But she used to keep her hair open so it was never really visible. Only at a party or something she would take her hair in front or do a high ponytail and only then it would be visible.