Three questions in strict order: integrity (has it changed?), then trust (does the identity chain to a recognised trust regime?), then durability (will it still verify years from now without anyone's help?). This is a ladder of necessary conditions, not a points total — a file receives the highest grade whose conditions it meets in full, and one failed gate caps it regardless of everything else.
The file proves who signed it and that nothing has changed, on its own, and the proof can be kept alive for decades. Embedded evidence packages and similar additions are shown alongside the grade; they do not change the letter.
This is what a properly signed document looks like. It proves who signed it, when, and that nothing has changed — on its own, offline, without the platform that made it.
An independent third party has proven when this was signed, and it will keep verifying for years.
Verifies today. There is no independent proof of when it was signed, and once the signing certificate expires or its revocation data goes offline, it may stop verifying entirely.
You can prove this file has not changed. You cannot prove who signed it. The result also states the grade the file’s own construction would reach with a certificate from a recognised provider — B or C — so a well-built document on a private root is not confused with a self-signed PDF.
Something was signed. This file cannot prove it. The proof sits with the signing platform, not with you. Nothing here is wrong — it is simply not self-proving.
This document does not prove what it claims. Do not rely on it without going back to the source.
No letter is issued when there is no signature and no evidence package to assess, or the file cannot be read. This is never shown as F. F means the document was checked and failed; absence of proof is a different statement from disproof.
Full criteria for every grade at documenttrustgrade.org →
The scale is open: anyone can apply it, and anyone can check a grade against it. Tindom’s part is the validation underneath — the signature, the certificate chain against the EU trusted lists and the other trust regimes the scale covers, revocation data and timestamps — and stating the result as a grade.
Every grade Tindom issues names the rubric version it was graded against and the date, so it can always be checked against exactly those rules. And it says what held the document back, and what would raise it.