RMA: Replace 'operation' with 'operator' where appropriate

[jaegerj]

Problem

"Operation" is used to describe the op argument for MPI_Accumulate, MPI_Get_accumulate and MPI_Fetch_and_op.
MPI 4.0 introduces an new meaning for "operation", and "operator" should be prefered instead.

Proposal

Replace "operation" and "reduce operation" with "\MPI/ operator" where appropriate

Changes to the Text

Replace "operation" and "reduce operation" with "\MPI/ operator" where appropriate

Impact on Implementations

None

Impact on Users

Better clarity in the standard

References

PR https://github.com/mpi-forum/mpi-standard/pull/490 provides a similar modification for the collective chapter (and a few references in other chapters, excluding RMA)

[devreal]

@jaegerj This does not only affect the RMA chapter but also applies to the collectives chapter, where reduction operations should become reduction operators (including user-defined reduction operators) to distinguish from reduction operations such as MPI_Reduce.

[devreal]

Argh, I just noticed that there was a separate PR for the collectives chapter. However, that PR and the associated issue are closed without the fix being merged. Is there an updated PR/issue for MPI 4.1?

[martinruefenacht]

This also affects the DSL as noted by @devreal in #637. I will create a branch for that aspect touching the binding blocks in chap-binding, chap-one-sided and chap-collective.

[jaegerj]

Collective chapter, in branch mpi-4.x, already contains the change operation -> operators. However, I just found some discrepancies.
With Dan, we have a branch to change "operators" to "\MPI/ Operators". I'll add the correction of the discrepancies in this branch.

[RolfRabenseifner]

Please be careful: We have MPI builtin operators like MPI_SUM and user defined operators defined with MPI_Op_create.
Please be careful that the changed wording does not look like that user defined operators are in future forbidden where they are currently allowed.

[devreal]

@jaegerj I guess I had found the instances where reduction operation is still used, e.g.,

Reduction operations can be queried for their commutativity.
or
Predefined Reduction Operations

With Dan, we have a branch to change "operators" to "\MPI/ Operators"

I agree with Rolf. Not sure what problem that would solve.

[jaegerj]

Noted. I'll just fix the missed "operations"->"operators" in a new branch and PR