The units used around GPS has always been interesting to me. I once received an email from you a vendor of a commercial GPS unit informing us of a bug "above Ma

The units used around GPS has always been interesting to me. I once received an email from you a vendor of a commercial GPS unit informing us of a bug "above Mach 15". For a scenario that pretty much only happens in space, talking about Mach 15 seemed very bizarre. The bug ended up being that they stored Doppler shift information in a signed 16-bit integer, which is fine on Earth but breaks in orbit.