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🗂️ What is DATA DIVISION?​

  • Defines variables used in the program.

  • Must declare data before use.

  • Optional but important.

  • Divided into sections: FILE, WORKING-STORAGE, LOCAL-STORAGE, LINKAGE

🧩 Important Sections​

  • FILE SECTION: File record structures.

  • WORKING-STORAGE: Constants, temp variables (initialized once).

  • LOCAL-STORAGE: Variables initialized every program run.

  • LINKAGE: Parameters passed by calling program.

🔢 Data Items & Levels​

  • 01: Record or elementary item (start Area A).

  • 02–49: Group or elementary item (Area A or B).

  • 66: RENAMES clause items.

  • 77: Independent data items (start Area A).

  • 88: Condition names.

🧱 Group vs Elementary Data Items​

Group: Contains smaller items, no PIC clause.

Elementary: No subdivisions, requires PIC clause.

📝 Variable Naming Rules​

  • Use alphabets, digits, hyphens.

  • Length 1 to 30 chars.

  • No reserved words or spaces.

  • Cannot start with special characters.

⚠️ FILLER​

  • Used for unnamed data fields.

  • Cannot be used in operations.

  • Useful for padding or reserved spaces.

🖼️ PICTURE Clause​

  • Defines data type, size, sign, decimals.

  • Numeric (9), Alphabetic (A), Alphanumeric (X).

  • Not for groups or level 88.

💡 VALUE Clause​

Initializes variables in WORKING-STORAGE only.

🔄 REDEFINES Clause​

  • Shares memory for variables with different formats.

  • Redefining & redefined items must be compatible & adjacent.

  • Not allowed on levels 01, 66, or 88.

🏷️ RENAMES Clause​

  • Assigns a new name to sequential data items at the same level.

  • Can not rename level 01 or 77.

  • Can not rename items with OCCURS clause.