The input source is a tiny X12/EDI file that contains just one transaction of function group "CT" and transaction set code "831", which is Application Control Totals. Just for reference, here are some other related transaction set codes:

816OROrganizational Relationships
820RAPayment Order/Remittance Advice
824AGApplication Advice
830PSPlanning Schedule with Release Capability
831CTApplication Control Totals
832SCPrice/Sales Catalog
835HPHealth Care Claim Payment/Advice
840RQRequest for Quotation
842NCNonconformance Report
843RRResponse to Request for Quotation
844CFProduct Transfer Account Adjustment
846IBInventory Inquiry/Advice
849CFResponse to Product Transfer Account Adjustment
850POPurchase Order
852PDProduct Activity Data
855PRPurchase Order Acknowledgment
856SHShip Notice/Manifest
857BSShipment and Billing Notice
861RCReceiving Advice/Acceptance Certificate
867PTProduct Transfer and Resale
870RSOrder Status Information
885UARetail Account Characteristics
997FAFunctional Acknowledgment