He is a member of the Cherokee Nation with interests ranging from model railroading to fireflies. And he puts it all out there on his personal webpage, updated regularly since 1996. There was a time when it was normal to stumble upon pages like this one.
From that document:> and some countries separate thousands groups with a thin space
Thin space (U+2009) is also how you are supposed to do it when using the SI unit system, according to the SI spec. For the decimal separator, the SI standard is to use which of '.' or ',' is customary.