Dear experts, sorry if this is a stupid question, but I was playing with offloading for the nvptx-none target and found different behavior between e.g. gfortran-10 on OpenSuse and the Nvidia compiler (nvfortran) for the attached code. With "nvfortran -mp=multicore offload-test.f90" the code prints: 2.000000 2000.000 s1: 1001000. s2: 1001000. With "/usr/bin/gfortran-10 -fopenmp -foffload=nvptx-none offload-test.f90": 2.00000000 2000.00000 s1: 1001000.00 s2: 0.00000000 The core difference between the evaluations s1 and s2 is: s1: !$omp target data map(a,s) !$omp target teams reduction(+:s) map(s) do i = 1, n s = s + a(i) end do !$omp end target teams !$omp end target data s2: !$omp target data map(a,s) !$omp target teams reduction(+:s) do i = 1, n s = s + a(i) end do !$omp end target teams !$omp end target data I was assuming that the map clause in the reduction should not be necessary, but the result seems to tell me that either I am wrong (and gfortran is right), or nvfortran is wrong. With OpenACC this seems to be different; at least a simple example I tried with the reduction within an !$acc data ... !$acc end data did not show unexpected behavior. Can anybody tell me that I am wrong (and point me to the right place in the OpenMP standard), or should I open a PR? Thanks Harald