What is the unit for ground speed reported by ADS-B?

Strangely enough, I'm having trouble finding the unit reported by ADS-B on the Internet. Many sites simply refer to it as "ground speed". Is it measured in KPH?

ADS-B* encodes the ground speed in NM/s (nautical miles per second) in $2^{15}$ increments of ≅ 0.22 knots each such that: