Whether field is a STORED ArcadeDB property — a declared attribute NOT in skip. It is the only kind of field a n.<field> Cypher reference (sort or a value-reading aggregate) can name. False for a calculation/aggregate NAME (not a declared attribute at all) and for a declared-but-skipped attribute (never persisted as a property). Drives the fail-closed guards on the record-read sort path (sort/3), the aggregate :first sort path, and the aggregate value-reading field: a non-stored field fails LOUD value-free rather than emitting n.<field> against a non-existent property, which ArcadeDB treats as null (a silently arbitrary sort / a silent default aggregate value).

Whether field may be translated into a Cypher VALUE expression — a stored property (stored_field?/2) that is not sensitive (app-side-encrypted binary; a plaintext op over ciphertext is meaningless). The classification predicate for Cypher value-translation. Query.Expression's Ref guard uses it; Filter.filterable_field?/2 is unified onto it in the filter-wiring task, eliminating the S6 divergence class (project_filter_guard_presence_predicate_coverage). Presence (is_nil) uses stored_field?/2 alone — a sensitive field IS presence-checkable (the documented oracle, D9).