Here are a few more edits -- against revision 3. -Adam I don't know if we want to list *every* section for the reduction collectives. (We don't do this for other collectives like alltoall, alltoallv, alltoalw) I think we could simplify a couple: p 1, lines 41-42 Simplify: "where the result is returned to all members of a group (Section 5.9.6 and Section 5.12.8) and a variation where the result is returned to only one member (Section 5.9 and Section 5.12.7)." to: "where the result is returned to all members of a group and a variation where the result is returned to only one member (Section 5.9, Section 5.12.7, and Section 5.12.8)." p 1, lines 47-48 Simplify: "(Section 5.11, Section 5.11.2, Section 5.12.10, and Section 5.12.11)" to: "(Section 5.11, Section 5.12.10, and Section 5.12.11)" Mixing call and operation p 2, lines 18-20 Change: "A blocking operation is complete as soon as the call returns. A nonblocking (immediate) call requires a separate completion operation" to: "A blocking operation is complete as soon as the call returns. A nonblocking operation requires a separate completion call" Missing a "nonblocking": p 50, line 5 "Similarly to the blocking case, collective operations ..." --> "Similarly to the blocking case, nonblocking collective operations ..." We should also stress local-ness of completion in the "i.e." phrase p 5, line 7 "i.e., the semantics of the operation are guaranteed" --> "i.e., for the caller, the semantics of the operation are guaranteed" Since we are now using the word "indicate" in the first sentence, it'd be good to use this same word in the following "also" sentence. p 50, line 10 "does not imply" --> "does not indicate" I think it'd read better to mention the "in place" buffer restriction following the other sentence about "in place" near the end. p 50, line 1-2, remove sentences "When using the "in place" option, ... Such buffers ... until the operation completes." p 51, lines 9-14: Split this paragraph into two and add the removed sentences from above (I also added "Once an operation is initiated"). The result paragraphs read: In terms of data movements, each nonblocking collective operation has the same effect as its blocking counterpart for the intracommunicators and intercommunicators after completion. Likewise, upon completion, nonblocking collective reduction operations have the same effect as their blocking counterparts, and the same restrictions and recommendations on reduction orders apply. The use of the "in place" option is allowed exactly as described for the corresponding blocking collective operations. When using the "in place" option, message buffers function as both send and receive buffers. Once an operation is initiated, such buffers should not be modified or accessed until the operation completes. Verb tense of "call" and keep the "only" keyword from blocking description: p 51, line 36 "the operation completes after every process in the communicator called MPI_IBARRIER" --> "the operation completes only after every process in the communicator calls MPI_IBARRIER" Expand intercommunicator sentence for MPI_Ibarrier p 51, lines 36-37 Replace: "On intercommunicators, the operation completes when the MPI_BARRIER call would return." with: "On intercommunicators, the operation completes for processes in one group (group A) of the intercommunicator only after all processes in the other group (group B) call MPI_IBARRIER."