Properties recorded in the file
A disclosure that the file records a title, subject, author, company, the application that saved it, or a custom property — text a reader never sees in the body.
How the text is hidden
RTF keeps document properties in metadata destinations: {\info{\title …}{\author …}{\doccomm …}}, plus {\*\userprops{\propname …}{\staticval …}} where Office writes a sensitivity label, SharePoint a content-type id and an editor its own state. The values are real prose and they are never displayed in the body of the document. They reach a reviewer only through the application's File → Properties dialog.
Why a model still reads it
The fields are stored as ordinary text and are read by extractors along with everything else, so an instruction written into a title or a company name arrives in a model's context while sitting somewhere a reviewer does not habitually look.
What we do about it
Metadata destinations set a suppressed flag, and computeReason answers document-property before it considers the generic ignorable-destination case, so a custom property gets the specific answer rather than the generic one. The pack rule is informational with action disclose, so it never moves a verdict, and it is one of only two techniques on the CERTIFIABLE_DISCLOSURES allowlist — a document does not lose certified for recording an author's name. The text is kept and handed back, and an instruction written into a property still escalates through the shared shape matcher. Visibility is editing-only: the properties dialog is two clicks away.
How often it fires
Not measured. We publish a rate only where one has been measured against a named corpus of the right format, and no figure exists for this technique yet. Absence means unknown — never low.
Check your own file
Three commands: a key, credit, a verdict.
Start with the API