What can be preserved?
Authorized original bytes/reference, exact source hash, reliable metadata, extractable content and explicit conversion evidence.
Forwardable migration brief
Libraries and archives
Keep original bytes and document what future readers need to interpret derivatives.
What cannot be recreated?
Missing history, certain authorship, custody, approvals, identity and semantics.
Safe pilot
Start with 100 representative authorized files, validate exceptions and expand only after reconciliation.
Everything at once?
No. Create new UDs now and migrate selected high-value families gradually.