Basis is the KIND of permission this publisher's data reaches you under: licence (an explicit grant), registry (the registry of record publishing for anyone to consult), operator (an operator's own machine-readable statement about its own network, published for third parties to filter by — not a licence, and not claimed as one), own (computed here), or none (nothing reaches you: the membership is held by the component that screens against it). It is on the wire so the licence position is an audit you can run.
Refusal is why this publisher's last take failed, if it did. The set keeps its previous version of this source and ages out visibly rather than silently shrinking.
Terms is the CITATION that basis points at — the licence identifier, the registry, or the operator publication. A source with no stated terms is not in the catalog.