OpenVMS National Character Set Utility Manual

This manual serves as a guide for system and application programmers on the OpenVMS National Character Set (NCS) Utility. It describes how to define custom collating sequences and conversion functions, register them in an NCS library, and make them accessible for use.

The document is divided into two main parts:

1. Introduction to the NCS Utility: This section details how to build NCS definition files. It covers the syntax and structure of these files, various expression types used for defining collating sequences (e.g., sequential, appended, modified, reversed, reordered) and conversion functions (e.g., sequential, modified, inverted, reordered), and the use of keyword clauses (CS, SEQUENCE, IDENT, MODIFICATIONS). It also mentions built-in definitions like _NATIVE and _IDENTITY.
2. NCS Command and Command Qualifiers: This part explains how to use the NCS Utility interactively via DIGITAL Command Language (DCL) commands and qualifiers. It outlines library operations such as creating, inserting, replacing, extracting, deleting, listing, compressing, and managing the data format of definition modules within an NCS library.

The manual clarifies that while the utility can be used programmatically via callable routines, its primary focus is on interactive library management and definition file creation. By default, NCS replaces modules in the default library, with most other functions requiring explicit command qualifiers.