Colon - Delimiter character
A colon (:) is a special character used as a delimiter or separator in various mainframe contexts, including JCL, REXX, TSO/ISPF commands, and embedded SQL. Its primary purpose is to logically separate elements within a statement, command, or data structure, indicating distinct parts or relationships. In the mainframe and z/OS environment, the colon (:) is a significant delimiter character used to separate or punctuate elements within various commands, statements, and data structures. It serves to define boundaries between different parts of a syntax, allowing parsers and interpreters to correctly understand and process instructions or data. Its specific meaning is context-dependent, varying across JCL, TSO commands, REXX scripts, and data streams.
Key Characteristics
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- Context-Dependent Role: The meaning and function of the colon are highly dependent on the specific language, utility, or command interpreter in which it is used.
- Separator for Paths: In JCL, it can separate multiple directory paths within the
PATHparameter of aDDstatement for z/OS UNIX System Services (USS) files, or concatenate load libraries inSTEPLIBusingSYSCAT. - Assignment and Scope in REXX: In REXX, it primarily denotes label definitions for branching or subroutine calls (
label:), acting as a target forSIGNALorCALLinstructions. - Host Variable Indicator in SQL: In embedded SQL for DB2 within application programs (e.g., COBOL, PL/I), a colon must precede host variables, distinguishing them from database column names.
- Environment Variable Delimiter: In z/OS UNIX System Services (USS), it functions as a standard path separator for environment variables like
PATHorLIBPATH, similar to other Unix-like operating systems.
Use Cases
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- **JCL
DD
- **JCL