I am not completely happy with the name format I have suggested for assertions. I would be glad to hear suggestions. Here is how I would cast each assertion. MPI_NO_EAGER_THROTTLE: This program does not depend on libmpi to provide an EAGER_THROTTLE semantic MPI_NO_REDUCTION_DETERMINISM This program does not depend on libmpi to provide a REDUCTION_DETERMINISM semantic MPI_NO_DATATYPE_HETEROGENEITY This program does not depend on libmpi to provide support for DATATYPE_HETEROGENEITY in communication MPI_NO_SEND_CANCEL This program does not depend on libmpi to provide a SEND_CANCEL semantic MPI_NO_ANY_SOURCE This program does not depend on libmpi to provide an ANY_SOURCE semantic MPI_NO_MPI_IO This program does not depend on libmpi to provide MPI_IO support etc In each case we are talking about something the MPI standard says must be provided by a compilant MPI implementation, just in case the application needs it. For each case there are application sthat do not need it. Does this help? Dick Treumann - MPI Team/TCEM IBM Systems & Technology Group Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601 Tele (845) 433-7846 Fax (845) 433-8363