There are SI, MKS, SGS, U.S., None and Custom System of units in Mathcad 15.
There are SI, SGS (not quite correct - without stat units) and U.S System of units in Mathcad Prime.
The base system of units in Europa, Canada, Russia etc is SI.
The base system of units in USA is U.S.
Do you know what country has the SGS as a base system of units?
I know 