Good Morning everyone. First time here, and it's because I have a Fortran+Polymorphism+MPI question. I'm getting unexpected results transferring an object over MPI. The object I'm sending EXTENDS an ABSTRACT object, and I'm using a CLASS pointer to the base object in the MPI_Send and Receive. Data from the base object is transferred, but not from the extended object, unless I'm using gfortran-7 and OpenMPI 2.1.1 built with gfortran-7 and gcc-7 - where data from the extended object is transferred, but not the data in the base class (which I find very strange). I've tried this using the Intel MPI (Version 2017 Update 1 Build 20161016 (id: 16418)) with ifort version 17.0.1 20161005 and gfortran-7 with a couple builds of OpenMPI. Any takers? I've got a 136 line Fortran program to demonstrate the problem. I'd like to know if I'm doing something wrong, or if I'm just expecting too much from the compiler and library implementers?