 Then, a numeric code identifies the individual route.A route with a 4-digit code contains no segment higher than 1,500 feet AGL, while a 3-digit code indicates that one or more segments of the route exist at altitudes higher than 1,500 feet AGL.For example, the route VR1234 would indicate a VFR route exclusively below 1,500 feet AGL, while IR567 would indicate an IFR route with at least one segment higher than 1,500 feet AGL.