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Date: Tue, 09 May 2000 09:09:38 -0500
To: mpi-core@XXXXXXXXXXX
From: William Gropp <gropp@XXXXXXXXXXX>
Subject: Another clarification
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The following question came up:  Suppose a datatype is created that has size 0; for example, a contiguous type with count 0 (the count is required to be non-negative, not positive).  A message is sent with this datatype and received, creating a status.  What value does MPI_Get_count or MPI_Get_elements return?  It could return 0, the count value specified by the user (just kidding!), MPI_UNDEFINED, or something else.
I propose the clarification that in this case, MPI_Get_count and MPI_Get_elements return 0.

Bill