On Tue, 2025-08-19 at 10:10 +0200, Thomas Schmitt wrote:
"This field shall not be used by UEFI firmware."
In practice, some EFI implementations interpret this "shall not" as
"must not" and refuse to use such a partition entry.
In ISO standardese, "shall [not]" is a requirement [prohibition], while "must" is the result of proving a theorem using other statements in the document.