DEC STD 145

DEC Standard 145 defines the DEC Representation of Data Values in ASCII Character Strings for Information Interchange Standard.

Key aspects of the document:

• Purpose: It establishes a standard for representing data in character strings to facilitate easy and efficient interchange between various DEC systems, architectures, and software.

• Extension of ANSI Standard: It explicitly extends the ANSI X3.42 standard ("American National Standard for the Representation of Numeric Values in Character Strings for Information Interchange") by adding specifications for:

  • Optional radix indications in numeric data values.
  • String data values.
  • Logical (boolean) data values.

• Scope: The standard applies to all DEC software products that produce or read character data files, including terminal files, language translators, interpreters, and editors.

• Data Types Covered: The document details the specific ASCII character string formats for:

  • Numeric Values: Including implicit-point, explicit-point unscaled, and explicit-point scaled representations (e.g., scientific notation).
  • String Data Values: Character strings, with rules for delimiters and embedded quotes.
  • Logical Data Values: Boolean representations (e.g., True/False).

• What it Doesn't Specify: The standard deliberately does not define:

  • The maximum number of characters in a data value.
  • Methods for delimiting data values or organizing them into larger aggregates (like records or arrays).
  • Mechanisms for communicating the accuracy of numeric values.
  • How to interpret a character string if it merely appears to be a data value but isn't intended as such.

• Formalism: It employs a defined syntactic metalanguage to formally specify the structure and rules for these data representations.

In essence, DEC Standard 145 provides a foundational set of rules for how different types of data should be formatted as ASCII text strings to ensure interoperability and consistent data exchange within the DEC ecosystem.