Open-Close data is a volume summary file for trading activity on the EDGX exchange. It summarizes and buckets the volume by origin (customer, professional customer, broker-dealer, and market maker), buying/selling, and opening/closing criteria. The customer and professional customer volume is further broken down into trade size buckets (less than 100 contracts, 100-199 contracts, greater than 199 contracts). Data for subscriptions begin on the first trade date from the order date. Historical backfills may be purchased separately; data currently goes back to 1/2/2018 and contains all series in an underlying security's chain-if it has volume.