docs: the clean-room policy and reconnaissance say the approach reduces legal risk, not that it removes it

CLEANROOM.md

@@ -1,9 +1,10 @@
 # Clean-room policy
 
 rvt-rs is a clean-room implementation of a reader for the Autodesk
-Revit on-disk format. Every byte-level finding in the repo is derived
-from **public** sources. This document states the policy in
-enforceable terms so contributors and auditors can verify.
+Revit on-disk format. Every byte-level finding in the repo must be
+derived from **public** sources and state the sources it rests on. This
+document states the policy in enforceable terms so contributors and
+auditors can verify.
 
 ## Accepted sources
 
@@ -119,10 +120,13 @@ forbidden source, the reviewer:
 - Trust with the Autodesk / ODA / buildingSMART ecosystem. A
   project that scrupulously respects IP boundaries is more
   credible and less likely to invite litigation threats.
-- Downstream users can ship rvt-rs in commercial products
-  (Apache-2 license + clean-room provenance = no viral-license
-  risk + no IP-contamination risk). Reading revit-ifc for what the
-  export writes, and never copying its code, keeps it that way.
+- Downstream users can ship rvt-rs in commercial products. The
+  Apache-2.0 license and recorded clean-room provenance are meant to
+  keep viral-license and IP-contamination risk low; no process can
+  rule such risk out, which is why the legal posture below asks users
+  with specific constraints to take their own advice. Reading
+  revit-ifc for what the export writes, and never copying its code,
+  is part of that discipline.
 - Contributors who want to work on the project without signing an
   NDA get a clear path.
 

docs/rvt-moat-break-reconnaissance.md

@@ -345,11 +345,11 @@ AI changes all four:
 
 ### 6.4 Regulatory & legal context
 
-- **Autodesk v. ODA (2006)** — trademark suit. Settled. Autodesk lost the ability to use trademark to stop RVT reimplementations.
-- **ODA BimRv SDK** — commercial, ~$500–5k/yr member pricing. Not available to non-members. Gated by NDA.
-- **No cryptographic protection on RVT files themselves** — confirmed in this recon. Data is structured; not obfuscated.
-- **GPL-3 / Apache-2 clean-room implementation has no legal risk** — DMCA doesn't apply (no DRM circumvention), copyright doesn't apply (interoperability exception under 17 USC 1201(f)).
-- **Autodesk Forge ToS** does restrict "deriving the RVT format" — but those ToS only bind Forge users, not independent researchers.
+- **Autodesk and the Open Design Alliance** — Autodesk's 2006 suit, over the TrustedDWG watermark the ODA's libraries wrote into DWG files, and the DWG trademark proceedings that followed concerned DWG, not RVT. The two announced a settlement of the trademark disputes on 2010-04-09 ([Autodesk's announcement](https://investors.autodesk.com/news-releases/news-release-details/autodesk-and-open-design-alliance-reach-agreement-autodesk-dwg)).
+- **ODA BimRv SDK** — a commercial SDK licensed to ODA members under their agreements. rvt-rs uses none of it (`CLEANROOM.md`).
+- **No encryption in the files read for this work** — their streams are structured data that rvt-rs inflates and reads without any key (§3.3: up to 17:1 on inflation, which encrypted data does not give). That covers the files in this repository's corpora, not every RVT file; [`compatibility.md`](compatibility.md) lists encrypted or password-protected files as unsupported.
+- **The project's clean-room approach is intended to reduce, not eliminate, legal risk.** In the United States, 17 U.S.C. § 1201(f) contains a limited interoperability provision subject to statutory conditions. This is not legal advice; the implications depend on the circumstances.
+- **Autodesk Platform Services (formerly Forge)** — rvt-rs does not use it or its terms.
 
 ## 7. Status & next steps