The document itself is paywalled like all the POSIX specifications, so here are some highlights courtesy of some comments at HackerNews, especially from a-french-anon.
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IMO the NUL-delimited options are by far the biggest win for shell scripting.
' '
will be the most commonly used addition, but"$(printf '...')"
was always an option before. You don’t really have an alternativeread -d ''
.