If you think the talk about ProMark (and ProFlex 800) fixing with GLONASS only is only hype, check this out:
In Carlson SurvCE V2.91 there is a new option “Use GLONASS Only”:
Checking the box turns off US SV tracking:
But the receiver still is able to compute a solution:
I don’t know why you would ever want to do that, but I am convinced that it really does work!