To: J3                                                     J3/26-116
From: HPC
Subject: Recommendation for DIN3a "Support atomic operations in local memory"
Date: 2026-February-11
References: 24-167, WG5/N2230, WG5/N2234, WG5/N2249

1. Background
=============

WG5/N2249 provides the list of accepted work items for the next revision of
ISO/IEC 1539:2023 (Fortran 202Y). That list currently includes accepted work
item:

  - DIN3a Add support for atomic operations in local memory
          Ref: N2230 "DIN Suggestions for F202Y" (other features requested
          in DIN3 were not accepted.)

This work item was initially added to the list by WG5 at the June 2024 meeting
in WG5/N2234. As indicated above, it comprises a small subset of the broader
item DIN3 proposed in WG5/N2230 (and subsequently mostly declined by WG5) to
expand support for APU processing. The remaining subset relevant to atomic
operations amounts to a two-sentence request with no specific rationale or use
cases. To our knowledge, no follow-up J3 papers have been published to further
support work item DIN3a or elaborate a proposed design for this feature in
isolation. Nevertheless, Info paper 24-167 rated item DIN3a with difficulty
level 5 ("Technical change likely to need more than two J3 meetings to
develop").

In June 2025, WG5 voted to remove the proposed asynchronous tasking feature
from Fortran 202Y work list item US04. With the deferral of asynchronous
tasking, it's even less clear how the underspecified DIN3a work item is
motivated to fit into the remaining language features in Fortran 202Y.

2. Subgroup Recommendation
==========================

The J3 HPC subgroup recommends that item DIN3a be removed (without prejudice)
from the Fortran 202Y work list. Proponents are welcome to resubmit the feature
request for a future revision, along with a more substantive rationale and
design sketch.


3. Resolution
=============

In passing this paper, INCITS/Fortran (J3) recommends to WG5 that item DIN3a be
removed from the work list for Fortran 202Y.

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