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>