Zip files can additionally store metadata in "extra file attributes". We believe these were intended as a cross-platform means of storing, say, Extended Attributes on OS/2 as well as user/group information. Crucially, it can store multiple file timestamps on Unix, including creation, modification *and* access time. (NB. You may not see access time changes under Linux system is your filesystems are mounted with `noatime` or `norelatime`).
When creating `.zip` files, it is [recommended to use the `--no-extra` / `-X`](https://lists.reproducible-builds.org/pipermail/rb-general/2024-March/003283.html) argument to not save these fields. It is also recommended that [developers unzip archives with `TZ=UTC`](https://lists.reproducible-builds.org/pipermail/rb-general/2023-April/002927.html).
