Unix Standards

See also: standards(7).

System V Interface Definition
SVID
(1985)
describes SVr2


X/Open Portability Guide
XPG1
(1985)
Based on SVID
Parts:
	1. The Common Applications Environment
	2. The X/OPEN System V Specification
	3. The C Language
	4. The X/OPEN ISAM Definition
	5. The X/OPEN COBOL Definition
	6. Source Code Transfer


SVID 2
System V Interface Definition version 2
describes SVr3
(1986)


X/Open Portability Guide issue 2
XPG2
(1987)
Volumes:
	1. System V Specification: Commands and Utilities
	2. System V Specification: System Calls and Libraries
	3. System V Specification: Supplementary Definitions
	4. Programming Languages (C, COBOL)
	5. Data Management (ISAM, SQL)


IEEE Std 1003.1-1988
POSIX.1-1988
"Portable Operating System Interface for Computing Environments"
by ANSI
Contents:
	System interfaces and headers


SVID 3
System V Interface Definition version 3
describes SVr4
(1989)


XPG3
(1989)
X/Open Portability Guide
superset of POSIX.1-1988


POSIX.1
POSIX.1-1990
IEEE Std 1003.1-1990
ISO/IEC 9945-1:1990
Only slight update of IEEE Std 1003.1-1988
Contents:
	System interfaces and headers


XPG4
X/Open Portability Guide
(1992)
superset of POSIX.1-1990, POSIX.2-1992, and POSIX.2a-1992


POSIX.2
IEEE Std 1003.2-1992
ISO/IEC 9945-2:1993
Contents:
	Shell and Utilities


SVID 4
System V Interface Definition version 4
(1995)
Updated for compliance with XPG4 and POSIX.1-1990
online


SUS (SUSv1)
XPG4v2
Single UNIX Specification
repackaging of XPG4v2 and other X/Open standards
UNIX 95


SUSv2
Single UNIX Specification version 2
XPG5
(1997)
UNIX 98
online


POSIX.1-2001
IEEE Std 1003.1-2001
The Open Group Base Specifications Issue 6
SUSv3
(2001)
revision and consolidation of the POSIX.1, POSIX.2,
and SUS standards into a single document
online


POSIX.1-2008
IEEE Std 1003.1-2008
The Open Group Technical Standard Base Specifications, Issue 7


POSIX.1-2013
IEEE Std 1003.1, 2013 Edition
The Open Group Base Specifications Issue 7
online