While not a definitive answer, a stroll through the Navworx debacle might give you a feel for meeting the 'performance criteria'. I never bothered to examine each weed (as in 'get down in...'), but it seems that the issues revolved more around what extra data the FAA requires to be embedded in the GPS output, than pure position accuracy. It's also informative to note that there are AMOCs (alternative means of compliance) for the Navworx, but each specifies a particular *IFR certified* GPS for the position source. None allow an open-ended 'meets performance criteria'.I find performance criteria in the regulations, but not a list of “approved position sources”. Can you provide a link to that requirement and list?