That sounds like our National Route Program (NRP), which uses a grid of waypoints known as High-Altitude Redesign (HAR) points over most of continental US, and allows the filing of routes that are very close to the Great Circle route between any two airports. It's great for transcontinental flights. Of course, the NRP is an RNAV-based setup, but I don't know what the Required Navigation Performance (RNP) is...

NRP, RNP, MNPS, B-RNAV, P-RNAV, GNE, oh my!

It's entertaining to be talking about the A-10 in this context. A-10 pilots call anything above 500 ft AGL the "bozosphere" and they think they need oxygen.