ISO 2047:1975

Overview

ISO 2047:1975 is an international standard published by the International Organization for Standardization (ISO) that defines graphical representations for the control characters of the 7-bit coded character set, specifically those from columns 0 and 1 of the ISO 646 standard. These control characters are typically non-printing and used in information processing and data transmission systems. The standard provides two modes of representation to enable the visualization of these normally invisible control codes, facilitating debugging, diagnostics, and data supervision.

The two modes included are:

• Graphical symbols: Specific single-character symbols designed to represent each control character.
• Alphanumeric representations: Two-character abbreviations derived from the standard 7-bit code table, making the control characters recognizable in text displays.

ISO 2047 also includes representations for the non-printing SPACE and DELETE characters, making it a comprehensive tool for controlling and displaying 7-bit coded control characters.

Key Topics

• Control Characters Coverage: Covers all control characters in columns 0 and 1 of the ISO 7-bit coded set, including NUL, SOH, STX, ETX, EOT, ENQ, ACK, BEL, BS, HT, LF, VT, FF, CR, SO, SI, DLE, DC1-4, NAK, SYN, ETB, CAN, EM, SUB, ESC, FS, GS, RS, US, SPACE, and DELETE.
• Graphical Representations:
  • Single-character symbols designed to visually denote control functions.
  • Two-character alphanumeric codes based on standard abbreviations (e.g., NUL for Null, LF for Line Feed).
• Practical Usage:
  • Visualization on punch card readers, teletypes, or printers.
  • Diagnostic displays for data communication debugging.
  • Software and hardware that need to display or log transmission control characters.
• Non-Printing Character Handling: Enhances understanding and error detection by making invisible control codes explicitly visible in user interfaces or printouts.
• Standard Relations: Builds on ISO 646, which defines the 7-bit coded character set for information interchange.

Applications

ISO 2047:1975 is crucial in various information processing and communication scenarios, including:

• Data Communication and Networking: Helps technicians and developers identify control characters during data interchange troubleshooting.
• Printing and Output Devices: Enables printers and displays to represent transmission control characters that would otherwise be invisible.
• Software Development: Useful for debuggers, terminal emulators, and diagnostic tools that need to expose non-printing control characters in logs or GUIs.
• Telecommunication Equipment: Standardizes the display of control functions on terminals and message processing systems.
• Information Exchange Systems: Facilitates error detection and correction by clearly showing control characters during data processing.

By standardizing graphical representations, ISO 2047 supports consistent interpretation and handling of control codes across different devices and applications worldwide.

Related Standards

• ISO 646: Defines the 7-bit coded character set for information interchange, which is the basis for the control characters represented in ISO 2047.
• ISO/IEC 2022: Specifies the use of control functions and character coding for information interchange.
• ITU-T V.24 / EIA RS-232: Standards defining signaling for serial data communication, where control character representation can be crucial.
• Unicode Standard: While more expansive, it includes representations for control characters, and ISO 2047’s graphic symbols have influenced visual control character displays.

Summary

ISO 2047:1975 offers practical, internationally recognized graphical symbols and alphanumeric codes to make the 7-bit control characters visible and understandable. This standard is vital for improving communication clarity, device diagnostics, and data processing integrity in systems handling text and binary data transmissions. Implementing ISO 2047’s representations enhances the reliability and user-friendliness of hardware and software managing control characters in the 7-bit code environment.