Modern Fortran's only parallel feature is coarrays, which operate at the whole program level. DO CONCURRENT is a serial construct with an unspecified order of

Modern Fortran's only parallel feature is coarrays, which operate at the whole program level. DO CONCURRENT is a serial construct with an unspecified order of iterations, not a parallel construct. A DO CONCURRENT loop imposes requirements that allow an arbitrary order of iterations but which are not sufficient for safe parallelization.