Communicator Attributes

MPI_Keyval_create: Deprecated - Use
MPI_Comm_create_keyval. 
MPI_Keyval_free: Deprecated - Use
MPI_Comm_free_keyval. 
MPI_Attr_put: Deprecated - Use
MPI_Comm_set_attr. 
MPI_Attr_get: Deprecated - Use
MPI_Comm_get_attr. 
MPI_Attr_delete: Deprecated - Use
MPI_Comm_delete_attr.