Submit a CSV of consortium searches (one search per row, one of each identifier). Always processed asynchronously (202 + batch id); poll GET /consortium/searches/batches/{batch_id} and download per-row results via /consortium/searches/batches/{batch_id}/download. Batches are capped at 40,000 rows. Allowed columns: reference_id, ein, phone, email, website, business_name, officer_first_name, officer_last_name, officer_state, address_street, address_city, address_state, address_zip, business_id.