This standard specifies dimensions, shapes, operating dimensions, etc. to ensure compatibility between semitrailer tractors and semitrailers that make up coupled vehicles.
JIS D 6603:1998 history
1998JIS D 6603:1998 Road vehicles -- Mechanical coupling between tractors and semi-trailers -- Interchangeability
1995JIS D 6603:1995 Interchange coupling dimensions of truck tractors and semitrailers