D035 - A derived row ships with the command that re-derives it

Status: decided Date: 2026-09-26

A format fact established by derivation from material, rather than cited from a source, is marked DERIVED in data/, and selfish derive <package>... re-checks it against packages the reader supplies. A claim survives only if every sample it can be tested on agrees.

Why: a cited row can be checked by opening its source; a derived row is only as good as its samples and method, and one nobody can re-run is indistinguishable from memory.

Rejected:

• Derived rows without a command: unverifiable by anyone else.
• Majority agreement: a format true of two packages in three is not a format.