fyi...anything in the CONUS with a 4 letter Alpha-numeric will never go on NADIN.
Example from this list....
U76 MOUNTAIN HOME ID *...his is Ok, because if ever routed via the NWSTG/WMSCR it would go as KU76
75IS CHICAGO/LURIE IL...Not ok...we do not route 5 letter idents. In this case K75IS
Users that get saddled with these 4 letter alpha-numerics due to the FAA rules won't see longline dissemination unless it's via another method, or the ident gets changed to a three letter alpha-numeric. The K indicates the product is from the CONUS, similarly a P indicates a geographical location like Alaska or the Pacific.
Mike