Pins 10, 51, 70, 71, 73, and 104–127 are reserved for Nordic's internal diagnostic purposes.
It is recommended to connect the Reserved pins to the application board mechanically and thermally, but to keep them electrically unconnected. To facilitate a simpler or more economical stencil design, Reserved pins 104–127 can be left electrically, mechanically, and thermally unconnected with no stencil openings for them.