A one-line Word setting can change a custom XML schema association

A consequential WordprocessingML change need not alter text, a relationship
target, or a visible page. A document can retain one direct w:attachedSchema
entry in Settings while changing its target namespace. A text-oriented review
has little reason to surface that stored association; a package-review tool
should be able to state it precisely.

Document Change Assurance Benchmark 0.19.0
adds its thirtieth deterministic pair:
binding.attached_custom_xml_schema_namespace_changed.

The baseline and candidate preserve their member set, stored text sequence, and
schema-association count. Only word/settings.xml changes, where one synthetic
namespace value is replaced.

A valid leaf, an intentionally narrow boundary

Microsoft documents
AttachedSchema
as an attached custom XML schema. The OOXML definition places the
w:attachedSchema CT_String leaf directly in document Settings. The fixture
models exactly that stored structure: one direct element, one w:val
attribute, no child markup or text, and no Settings relationship part.

word/settings.xml                         only changed package member
  w:attachedSchema w:val="namespace"     one valid direct leaf on each side

word/_rels/settings.xml.rels              absent on both sides

The case is not a schema-validation experiment. It has no schema payload; does
not locate, retrieve, resolve, or load a schema; does not validate custom XML;
and does not open Word or claim host behavior. The synthetic values use the
reserved example.invalid domain.

Public truth without publishing the namespace

The target-free oracle reports only:

{
  "binding": "custom_xml_schema",
  "kind": "attached_custom_xml_schema_namespace_changed",
  "source": "word_settings"
}

It excludes both namespace identifiers, Settings-part paths, relationship
information, and private fingerprints. Structural validation independently
checks exact leaf shape, the one-member boundary, absence of a Settings
relationship part, stable package topology, unchanged stored text, deterministic
regeneration, and the absence of namespace material from public truth.

A released consumer without a value leak

The optional DocFence 0.29.0
adapter reaches a strict 30/30 score from two aggregate observations:
attached_custom_xml_schema_inventory_changed and a fixed
attached_custom_xml_schema_count of one. It never consumes a namespace,
Settings path, or private fingerprint.

Hosted CI passed for the release commit and tag. Clean wheel and source archive
installs validate the bundled 30-case corpus. The public
Hugging Face dataset
mirror was byte-verified against the generated tree and validated directly
after download.

python -m pip install https://github.com/SybilGambleyyu/document-change-benchmark/releases/download/v0.19.0/document_change_benchmark-0.19.0-py3-none-any.whl
dcab validate
dcab docfence-observations --executable docfence --output observations.json
dcab score --observations observations.json --strict

DCAB keeps fixture schema version 1: this is one exact static-review fact, not
a schema resolver, document client, renderer, validator, or universal policy
claim. Read the canonical release note
for the complete package and privacy contract.