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Pass 11 follow-up: disambiguate 'reserved built-in tags' in Appendix E 

The Canonical Byte-Layout Reference used the phrase 'reserved built-in
tags' in two scopes: the system-derived-identifier section called it the
closed set of three (MUSCSVCE/MUSCSPCH/MUSCSANM), while the domain-tag
registry calls eleven tags 'reserved built-in'. The source section
(req:graph:system-derived) qualifies the three as tags 'for
system-derived identifiers'; the consolidation had dropped that
qualifier, leaving the single-import appendix internally ambiguous for
the Binary Format companion author.

- Restore the scope qualifier and cross-reference the full registry,
  noting the other reserved tags feed plain hashing preimages, not the
  system-derived counter.
- Tighten the 'canonical' gloss: canonical tags produce identifiers and
  content hashes that are part of the interoperable, durably persisted
  form (not loosely 'document state', which misreads the storage-layer
  chunk/manifest/blob tags).

Spec-text only; rebuilds clean (0 undefined refs, 261 pages, no new
overfull boxes). No code or byte-layout change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Levi Neuwirth 2026-06-22 14:35:30 -04:00
parent dffac4c744
commit 83bc202ff6
2 changed files with 10 additions and 5 deletions
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spec/core_spec.tex
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@ -13432,10 +13432,13 @@ counter-allocated. They share one function
(\texttt{0xffff\_ffff\_ffff\_ffff}) identifier is (\texttt{0xffff\_ffff\_ffff\_ffff}) identifier is
$\mathrm{BE\_u64}(\mathrm{BLAKE3}(\texttt{domain\_tag} \Vert $\mathrm{BE\_u64}(\mathrm{BLAKE3}(\texttt{domain\_tag} \Vert
\texttt{canonical\_inputs})[0..8])$. The domain tag is exactly eight \texttt{canonical\_inputs})[0..8])$. The domain tag is exactly eight
bytes. The reserved built-in tags are the closed set bytes. The reserved built-in tags \emph{for this derivation} are the
\{\texttt{MUSCSVCE}, \texttt{MUSCSPCH}, \texttt{MUSCSANM}\}; tags closed set \{\texttt{MUSCSVCE}, \texttt{MUSCSPCH}, \texttt{MUSCSANM}\}
introduced by registered extensions \MUST{} begin with \texttt{MUSCS}, --- the three system-derived-identifier tags only; the other reserved
be exactly eight bytes, and not collide with the reserved three. domain tags catalogued in Section~\ref{sec:bytes:tags} feed plain
hashing preimages, not this counter. Tags introduced by registered
extensions \MUST{} begin with \texttt{MUSCS}, be exactly eight bytes,
and not collide with the reserved three.
\section{Discriminant tables, derivations, and encodings} \section{Discriminant tables, derivations, and encodings}
\label{sec:bytes:tables} \label{sec:bytes:tables}
@ -13584,7 +13587,9 @@ be exactly eight bytes, and not collide with the reserved three.
Every reserved built-in eight-byte domain tag, in one place, plus the Every reserved built-in eight-byte domain tag, in one place, plus the
\texttt{MUSCLOID} Track-A target. The nine \emph{canonical} tags --- \texttt{MUSCLOID} Track-A target. The nine \emph{canonical} tags ---
whose preimages produce content that enters document state --- are whose preimages produce identifiers and content hashes that are part of
the interoperable, durably persisted form every conforming
implementation must reproduce bit-identically --- are
listed first; \texttt{MUSCFNTM} and \texttt{MUSCLOID} are listed first; \texttt{MUSCFNTM} and \texttt{MUSCLOID} are
\emph{non-canonical} (layout-only) and listed last, for completeness \emph{non-canonical} (layout-only) and listed last, for completeness
(see Section~\ref{sec:bytes:deferred}). Registered extensions may (see Section~\ref{sec:bytes:deferred}). Registered extensions may