Exact - Precise match

Key Characteristics

• • Byte-for-Byte Comparison: Typically involves a direct, byte-level comparison of the underlying EBCDIC or ASCII representations of the data.
  • Case Sensitivity: Often implies that the comparison is case-sensitive, meaning 'ABC' is not an exact match for 'abc', particularly in z/OS dataset names, UNIX System Services paths, or specific application data.
  • Length Sensitivity: Requires the compared items to have the same effective length; padding with spaces or nulls can significantly affect the outcome unless explicitly handled by the comparison logic.
  • No Wildcards or Patterns: Excludes the use of wildcard characters (*, %, ?) or regular expressions; the match must be literal and complete.
  • Binary Equivalence: For numeric data, it means the binary representations must be identical, not just the perceived value (e.g., a PIC 9(3) field with value 123 is not binary equivalent to a PIC 9(5) field with value 00123 if the storage formats differ).

Use Cases

• • Data Validation and Integrity: Ensuring input data fields (e.g., transaction codes, customer IDs) precisely match expected values defined in COBOL programs or database schemas.
  • Resource Access Control: Matching user IDs, group names, or resource profiles in security systems like RACF (Resource Access Control Facility) for authorization decisions, where a precise identity is crucial.
  • JCL Conditional Processing: Using IF/THEN/ELSE statements or COND parameters where return codes from previous steps or symbolic parameters must exactly match specified values to control job flow.
  • Database Queries: Performing SELECT statements with WHERE clauses that require exact equality (=) for specific column values in DB2, IMS, or VSAM KSDS files to retrieve specific records.
  • File and Member Identification: Locating specific datasets, PDS/PDSE members, or z/OS UNIX files by their exact name when performing utility operations or program access.

Related Concepts