1. Overview of the BASIC Language
  This brief overview highlights the features of the OpenVMS
  implementation of BASIC. The features listed here are
  described fully in subsequent chapters of this manual, as
  well as in the other two manuals in the documentation set.

  BASIC was originally developed for students with little
  or no programming experience. Since then, BASIC has
  become one of the most widely used programming languages
  and is available on almost every computer system. The
  OpenVMS implementation of BASIC has evolved beyond the
  original design; however, it still supports all of the traditional
  features of the original language in addition to more recent
  programming techniques. It has become much more than
  a teaching tool and is used in a wide variety of sophisticated
  applications.

  BASIC is a powerful structured programming language
  designed for novice and application programmers alike. The
  language provides both a highly interactive programming
  environment and a high-performance development language.
  BASIC supports the following language constructs:

  .
        Code without line numbers (traditional line numbers are
        optional)
  .
        Control structures, such as SELECT CASE
  .
        Explicit variable declarations
  .
        Capabilities for handling dynamic strings
  .
        Adaptable file-handling capabilities for terminal-format
        files, and the full range of RMS facilities
  .
        Global and local run-time error handling with WHEN
        ERROR blocks
  .
        Compile-time directives
  .
        A variety of data types, including packed-decimal and
        user-defined records
  .
        Extensive error checking with meaningful error
        messages
  .
        Thirty-one character names for variables, labels,
        functions, and subprograms

  BASIC uses the OpenVMS operating system to its full
  advantage and is integrated with many other Digital
  products. In particular, BASIC supports:

  .
        Interactive graphics (VAX BASIC only)

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  .
        The OpenVMS systems standard calling procedures
  .
        Record definitions included from the OpenVMS Common
        Data Dictionary
  .
        Code analysis with the DEC Performance and Coverage
        Analyzer (PCA)
  .
        Creation of code with the DEC Language-Sensitive Editor
        (LSE)
  .
        Extensive online language help
  .
        Exchange of data with other systems using DECnet

  BASIC supports the features of other versions of BASIC,
  including PDP-11 BASIC-PLUS-2. BASIC is a functional
  superset of BASIC-PLUS-2. Compatibility flags for BASIC-
  PLUS-2 and ANSI Minimal BASIC allow you to check
  whether the programs will run on other systems.

  When you write programs in BASIC, you can choose between
  two program development methods: developing programs at
  DCL command level or developing programs from within
  the BASIC environment

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                                        . When you develop programs at
  DCL level, you write your source program with a text editor,
  then compile, link, and run the program with commands
  to the OpenVMS operating system. Alternatively, when you
  develop programs within the BASIC environment, you type
  the DCL command BASIC to enter the environment, enter
  your program, then execute it with the BASIC command
  RUN.