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+# Reference validation message sources
+
+## Grouped required-field errors
+- The string `"At least one of the following fields is required: …"` is produced in `orCheck` inside `frontend/src/shared/validators/reference.ts`.
+- `orCheck` builds the list of field keys based on `ref_type_id` and checks whether any of those fields contain a non-empty string. When none do, it returns the concatenated message with the raw field names.
+- `validateReference` wires `orCheck` into the validators for `title_primary`, `title_secondary`, `title_series`, and `gen_notes`, so the message appears both in inline errors and aggregate validation results.
+
+## Display labels for reference fields
+- Human-readable labels per reference type come from the database table `ref_field_name` (via Prisma model `ref_field_name`), which stores `ref_field_name` (display text) alongside `field_name` (schema key) scoped by `ref_type_id`.
+- The backend returns these labels through `getReferenceTypes` in `backend/src/services/reference.ts`, which fetches `ref_ref_type` records including their `ref_field_name` children.
+- On the frontend, `ReferenceTab` (`frontend/src/components/Reference/Tabs/ReferenceTab.tsx`) reads `selectedRefType.ref_field_name` to render form controls with the per-type display labels (e.g., `field.ref_field_name`).
+- These labels currently are not reused by the validator when constructing the grouped required-field message; the message still uses the raw field keys from `orCheck`.