2021 Document 6209 is a reference guide which contains ADP and IDRS data relative to various components of the IRS. It is updated annually. Table of ContentsPDFSection 1, GlossaryPDFSection 2, Tax Returns and FormsPDFSection 3, Tax Return InformationPDFSection 4, Document Locator NumberPDFSection 5, Debtor Master FilePDFSection 6, Initiating and Monitoring Refund Check Tracing ActionPDFSection 7, Automated Non-Master FilePDFSection 8A, Master File Codes - Transaction, MF and IDRS Collection Status, Freeze and IDRS Status 48, Restrictive and Filing RequirementsPDFSection 8B, Master File Codes - Unpostable and ResequencePDFSection 8C, Master File Codes - Source, Reason, Hold, Priority, Item Adjustment & Credit Reference, NMF Abstract, Underreporter, Process, No Merge Reason, EPPDFSection 9, Notices and Notice CodesPDFSection 10, Penalty and Interest ProvisionsPDFSection 11, CollectionPDFSection 12, ExaminationPDFSection 13, Appeals and TE/GEPDFSection 14, Integrated Data Retrieval System (IDRS)PDFSection 15, Other Systems CADE, CADE 2, SCRIPTS, CFOL and FTDPDFSection 16, Julian Date, Cycle and Notice CalendarsPDFAppendixPDF