BeginnerFAQs
Why is everything in capitals?
A short answer with a genuinely useful consequence.
Early terminals and punched-card equipment supported a single case, and the conventions stuck. Dataset names, JCL and traditional COBOL source are uppercase, and the system does not distinguish case in most of these contexts.
Where it stops being true
- z/OS Unix file names are case-sensitive, like any Unix.
- Java, Python and modern COBOL source can be mixed case.
- Data content has always been case-sensitive; only the naming conventions are not.
- The ISPF editor has a CAPS setting — CAPS ON silently uppercases what you type, which surprises people editing Unix paths or SQL string literals.
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