OpenVMS Command Definition, Librarian, and Message Utilities Manual

This manual, published in December 1995, is designed for programmers and general users of the OpenVMS operating system. It provides comprehensive guidance on three key utilities:

1. Command Definition Utility (CDU): This utility is used to modify the DIGITAL Command Language (DCL) by creating, deleting, or changing command definitions in command tables. It covers defining command syntax, parameters, and qualifiers, and linking commands to specific routines or executable images. Users can modify their process command table, the system-wide DCL table (with CMKRNL privilege), or create object modules for new command tables.
2. Librarian Utility (LIBRARIAN): This utility enables the creation, access, and maintenance of various types of libraries, including object, macro, help, text, and shareable image libraries. It details the structure of libraries, how module names and global symbols are handled (including character case sensitivity), and how to save disk space by storing data in a reduced format. It also describes how to format and retrieve help text modules.
3. Message Utility (MESSAGE): This utility allows users to supplement standard OpenVMS system messages with their own custom messages. It explains how to construct message source files, define message codes (incorporating severity, facility, and message number), compile these files into object modules, and link them with programs. The manual also covers the use of message pointers, which provide flexibility in managing message texts, such as for multilingual applications, without requiring recompilation of the main program.

The document supersedes previous OpenVMS documentation for AXP Version 1.5 and VAX Version 6.0, and is applicable to OpenVMS Alpha Version 7.0 and OpenVMS VAX Version 7.0.