Table of Contents
Standards
/usr/group
Prepared on January 17, 1984, the /usr/group standard is an early UNIX standard proposed by the /usr/group international network of UNIX users. This document was published along with the “Reviewer's Guide to the PROPOSED /usr/group Standard” as compiled March 14, 1984 and prepared by David L. Buck, which contains notes on the standard as well as a few focused papers on specific features such as file locking interfaces.
From the abstract:
This document describes a Standard for computer operating systems that are functionally compatible with the UNIX operating system developed by AT&T Bell Laboratories. In its present form, the document focuses primarily on the “C” Language interface to the operating system. This document is largely based on UNIX System III, but wherever possible, compatibility with UNIX Version 7 has been maintained.
This document is intended to be used by both application and system vendors to assist with the development of computer software which is portable across a large number and wide variety of computer systems.
System V Interface Definition
System V Interface Definition Issue 2
System V Interface Definition Issue 4 (Bottom of Page)
The System V Interface Definition is a series of publications describing the minimum required user and application interface expected of UNIX systems published as System V compatible. Four known issues exist, published in 1985, 1986, 1992, and 1995, which cover System V Release 2.0, 3.0, 4.0, and 4.2 respectively.
As the SVID was more particular to UNIX System V, it contains many components not found in the POSIX standard.
From the introduction of the Fourth Edition:
The System V Interface Definition (SVID) is intended for use by anyone who must understand the operating system components that are consistent across all System V environments. As such, its primary audience is the application developer who is building C language application programs having source code that must be portable from one System V environment to another. A system builder should also view these volumes as necessary tools for supporting a System V environment that will host such applications.
POSIX/IEEE 1003
IEEE 1003.1, otherwise known as the POSIX standard, is published by the IEEE and is the current basis of the Single UNIX Specification as maintained and enforced by The Open Group. Drawing from both the /usr/group and System V Interface Definition standards, POSIX aims to be a vendor-neutral standard applicable to diverse operating systems presenting a UNIX-like application programming interface.
While IEEE 1003.1 itself merely defines the C language interfaces for system services, additional 1003-family standards exist, such as 1003.2, defining the user-level commands available on UNIX systems.
From the foreword of IEEE 1003.1-1988:
The purpose of this standard is to define a standard operating system interface and environment based on the UNIX Operating System documentation to support application portability at the source level. This is intended for systems implementors and applications software developers.
The foreword goes on to describe the derivation of this standard:
The various interface facilities described herein are based on the 1984 /usr/group Standard derived and published by the /usr/group Standards Committee, Santa Clara, California. The 1984 /usr/group Standard and subsequent work of the 1003.1 Working Group is largely based on UNIX Seventh Edition, UNIX System III, UNIX System V, 4.2BSD, and 4.3BSD documentation, but wherever possible, compatibility with other systems derived from the UNIX operating system, or systems compatible with that system, has been maintained.
Spec 1170/Single UNIX Specification
The Open Group Base Specifications Issue 6 The Open Group Base Specifications Issue 7
Spec 1170, now known as the Single UNIX Specification, is a standard maintained by The Open Group, consisting of the former X/Open and Open Software Foundation organizations. This standard, which extends IEEE 1003/POSIX, is the primary standard administered by The Open Group today and the standard currently applied to systems wishing to utilize the UNIX trademark.
Above is Go Solo, an informative work published by X/Open in 1995 with the initial version of the Single UNIX Specification included on a CD-ROM. From the foreword:
Go Solo is designed as an aid to understanding the Single UNIX Specification as well as a means of delivering 2,700 pages of X/Open Specifications in a convenient and easily accessible media, namely on CD-ROM with an SGML-based browser.