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in the Parallelism TS 2You can use the issue tracker of this repository to submit feedback on the Parallelism TS 2 (Clause 9: "Data-Parallel Types"). Of course you can also write and submit your own paper to the committee. In any case, the feedback needs to be published, so that the C++ committee can act on it.
Relevant WG21 paper asking for specific feedback: P1915.