PROV-DM (World Wide Web Consortium Recommendation, April 30, 2013) models provenance: production history. Its overview examples are non-normative—explanations, not compliance rules. An entity is a thing with some fixed features, such as one file version; an activity works on things over time, such as editing; an agent bears responsibility for work or output, such as an editor or software. Derivation means producing something based on an earlier thing; a revision produces a changed version. Illustratively, editing version 1 into version 2 is a revision. Merely reading a background note while producing version 2 does not establish derivation from that note: the input must affect the output. PROV leaves determining that influence to other means.