I have heard from several people that the CMR and CMR+ solutions for the Iowa DOT RTN system are single base station solutions only. I think that this means that if I have a field that is over 6-8 miles away from a base I can not expect sub inch accuracy from the corrections.

 I also have heard that the Trimble ag receivers can only accept CMR and CMR+ but not RTCM (any version) to get true RTK accuracy. Does anyone have any more information about this?