# Ancillary data w/ Io

**URL:** <https://ziggit.dev/t/ancillary-data-w-io/16680>\
**Category:** Help\
**Tags:** standard-library\
**Created:** [July 13, 2026, 4:08am UTC](https://ziggit.dev/t/ancillary-data-w-io/16680 "2026-07-13T04:08:56Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rosew0od](https://ziggit.dev/user_avatar/ziggit.dev/rosew0od/32/7663_2.png) [@rosew0od](https://ziggit.dev/u/rosew0od)\
**Post date:** [July 13, 2026, 4:08am UTC](https://ziggit.dev/t/ancillary-data-w-io/16680/1 "2026-07-13T04:08:56Z")

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Is there a way to send ancillary data with 0.16 Io, and if not, is there a way to cleanly integrate it into the io system?

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**Author:** ![lalinsky](https://ziggit.dev/user_avatar/ziggit.dev/lalinsky/32/3720_2.png) [@lalinsky](https://ziggit.dev/u/lalinsky)\
**Post date:** [July 13, 2026, 4:12am UTC](https://ziggit.dev/t/ancillary-data-w-io/16680/2 "2026-07-13T04:12:16Z")

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Yes, but only over datagram sockets, not connected ones. It’s currently a known limitation, but fixing Io doesn’t seem to be the priority for the next couple of Zig releases.

[https://codeberg.org/ziglang/zig/issues/32093](https://codeberg.org/ziglang/zig/issues/32093)

[https://codeberg.org/ziglang/zig/issues/31259](https://codeberg.org/ziglang/zig/issues/31259)

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**Author:** ![alanza](https://ziggit.dev/user_avatar/ziggit.dev/alanza/32/6006_2.png) [@alanza](https://ziggit.dev/u/alanza)\
**Post date:** [July 13, 2026, 4:00pm UTC](https://ziggit.dev/t/ancillary-data-w-io/16680/3 "2026-07-13T16:00:50Z")

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“for the next couple” seems to directly contradict what Andrew wrote [here](https://ziggit.dev/t/state-of-networking-in-std-io/16553/11) in response to you.

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**Author:** ![lalinsky](https://ziggit.dev/user_avatar/ziggit.dev/lalinsky/32/3720_2.png) [@lalinsky](https://ziggit.dev/u/lalinsky)\
**Post date:** [July 13, 2026, 4:24pm UTC](https://ziggit.dev/t/ancillary-data-w-io/16680/4 "2026-07-13T16:24:14Z")

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Andrew expressed that maybe we can discuss the strategy in a few weeks. Zig 0.17 was supposed to be a short cycle, so let’s just say I’m not as optimistic about 0.18. I’ll be extremely happy to he proven wrong.

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**Author:** ![hemisputnik](https://ziggit.dev/user_avatar/ziggit.dev/hemisputnik/32/9625_2.png) [@hemisputnik](https://ziggit.dev/u/hemisputnik)\
**Post date:** [July 23, 2026, 2:01am UTC](https://ziggit.dev/t/ancillary-data-w-io/16680/5 "2026-07-23T02:01:23Z")

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I actually put up a PR for exchanging control data with `Stream` just now!

[https://codeberg.org/ziglang/zig/pulls/36277](https://codeberg.org/ziglang/zig/pulls/36277)