# man > standards(7)

[_standards_(7)](https://www.chedong.com/phpMan.php/man/standards/7/markdown)                      Miscellaneous Information Manual                      [_standards_(7)](https://www.chedong.com/phpMan.php/man/standards/7/markdown)

## NAME
       standards - C and UNIX Standards

## DESCRIPTION
       The STANDARDS section that appears in many manual pages identifies various standards to which
       the documented interface conforms.  The following list briefly describes these standards.

       **V7     **Version  7  (also  known as Seventh Edition) UNIX, released by AT&T/Bell Labs in 1979.
              After this point, UNIX systems diverged into two main dialects: BSD and System V.

       **4.2BSD **This is an implementation standard defined by the 4.2 release of the _Berkeley_ _Software_
              _Distribution_, released by the University of California  at  Berkeley.   This  was  the
              first  Berkeley release that contained a TCP/IP stack and the sockets API.  4.2BSD was
              released in 1983.

              Earlier major BSD releases included _3BSD_ (1980), _4BSD_ (1980), and _4.1BSD_ (1981).

       **4.3BSD **The successor to 4.2BSD, released in 1986.

       **4.4BSD **The successor to 4.3BSD, released in 1993.  This was the last major Berkeley release.

### System V
              This is an implementation standard defined by AT&T's milestone  1983  release  of  its
              commercial  System  V (five) release.  The previous major AT&T release was _System_ _III_,
              released in 1981.

### System V release 2 (SVr2)
              This was the next System V release, made in 1985.  The SVr2 was formally described  in
              the _System_ _V_ _Interface_ _Definition_ _version_ _1_ (_SVID_ _1_) published in 1985.

### System V release 3 (SVr3)
              This was the successor to SVr2, released in 1986.  This release was formally described
              in the _System_ _V_ _Interface_ _Definition_ _version_ _2_ (_SVID_ _2_).

### System V release 4 (SVr4)
              This  was  the  successor  to SVr3, released in 1989.  This version of System V is de‐
              scribed in the "Programmer's Reference Manual: Operating  System  API  (Intel  proces‐
              sors)" (Prentice-Hall 1992, ISBN 0-13-951294-2) This release was formally described in
              the _System_ _V_ _Interface_ _Definition_ _version_ _3_ (_SVID_ _3_), and is considered the definitive
              System V release.

       **SVID 4 **System  V  Interface  Definition  version  4,  issued  in  1995.   Available online at
              ]8;;<http://www.sco.com/developers/devspecs/>\<http://www.sco.com/developers/devspecs/>]8;;\.

       **C89    **This was the first C language standard, ratified by ANSI (American National  Standards
              Institute) in 1989 (_X3.159-1989_).  Sometimes this is known as _ANSI_ _C_, but since C99 is
              also an ANSI standard, this term is ambiguous.  This standard was also ratified by ISO
              (International  Standards Organization) in 1990 (_ISO/IEC_ _9899:1990_), and is thus occa‐
              sionally referred to as _ISO_ _C90_.

       **C99    **This revision of the C  language  standard  was  ratified  by  ISO  in  1999  (_ISO/IEC_
              _9899:1999_).  Available online at ]8;;<http://www.open-std.org/jtc1/sc22/wg14/www/standards>\<http://www.open-std.org/jtc1/sc22/wg14/www/standards>]8;;\.

       **C11    **This  revision  of  the  C  language  standard  was  ratified  by ISO in 2011 (_ISO/IEC_
              _9899:2011_).

       **LFS    **The Large File Summit specification, completed in 1996.   This  specification  defined
              mechanisms that allowed 32-bit systems to support the use of large files (i.e., 64-bit
              file offsets).  See ]8;;<https://www.opengroup.org/platform/lfs.html>\<https://www.opengroup.org/platform/lfs.html>]8;;\.

### POSIX.1-1988
              This  was the first POSIX standard, ratified by IEEE as IEEE Std 1003.1-1988, and sub‐
              sequently adopted (with minor revisions) as an ISO standard in 1990.  The term "POSIX"
              was coined by Richard Stallman.

### POSIX.1-1990
              "Portable Operating System Interface for Computing  Environments".   IEEE  1003.1-1990
              part 1, ratified by ISO in 1990 (_ISO/IEC_ _9945-1:1990_).

### POSIX.2
              IEEE  Std  1003.2-1992,  describing  commands  and  utilities, ratified by ISO in 1993
              (_ISO/IEC_ _9945-2:1993_).

       **POSIX.1b **(formerly known as _POSIX.4_)
              IEEE Std 1003.1b-1993, describing real-time facilities for portable operating systems,
              ratified by ISO in 1996 (_ISO/IEC_ _9945-1:1996_).

       **POSIX.1c **(formerly known as _POSIX.4a_)
              IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces.

### POSIX.1d
              IEEE Std 1003.1d-1999, which describes additional real-time extensions.

### POSIX.1g
              IEEE Std 1003.1g-2000, which describes networking APIs (including sockets).

### POSIX.1j
              IEEE Std 1003.1j-2000, which describes advanced real-time extensions.

### POSIX.1-1996
              A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c.

       **XPG3   **Released in 1989, this was the first release of the X/Open  Portability  Guide  to  be
              based on a POSIX standard (POSIX.1-1988).  This multivolume guide was developed by the
              X/Open Group, a multivendor consortium.

       **XPG4   **A  revision of the X/Open Portability Guide, released in 1992.  This revision incorpo‐
              rated POSIX.2.

       **XPG4v2 **A 1994 revision of XPG4.  This is also referred to as _Spec_ _1170_, where  1170  referred
              to the number of interfaces defined by this standard.

### SUS (SUSv1)
              Single  UNIX  Specification.   This was a repackaging of XPG4v2 and other X/Open stan‐
              dards (X/Open Curses Issue 4 version 2, X/Open  Networking  Service  (XNS)  Issue  4).
              Systems conforming to this standard can be branded _UNIX_ _95_.

       **SUSv2  **Single  UNIX  Specification  version  2.   Sometimes also referred to (incorrectly) as
              _XPG5_.  This standard appeared in 1997.  Systems conforming to  this  standard  can  be
              branded _UNIX_ _98_.  See also ]8;;<http://www.unix.org/version2/>\<http://www.unix.org/version2/>]8;;\.)

### POSIX.1-2001
       **SUSv3  **This  was a 2001 revision and consolidation of the POSIX.1, POSIX.2, and SUS standards
              into  a  single  document,  conducted  under  the  auspices  of   the   Austin   Group
              ]8;;<http://www.opengroup.org/austin/>\<http://www.opengroup.org/austin/>]8;;\.     The    standard    is    available   online   at
              ]8;;<http://www.unix.org/version3/>\<http://www.unix.org/version3/>]8;;\.

              The standard defines two levels of conformance: _POSIX_ _conformance_, which is a baseline
              set of interfaces required of a conforming system; and _XSI_  _Conformance_,  which  addi‐
              tionally  mandates  a  set of interfaces (the "XSI extension") which are only optional
              for POSIX conformance.  XSI-conformant systems can be branded _UNIX_ _03_.

              The POSIX.1-2001 document is broken into four parts:

              **XBD**: Definitions, terms, and concepts, header file specifications.

              **XSH**: Specifications of functions (i.e., system calls and library functions  in  actual
              implementations).

              **XCU**:  Specifications  of  commands and utilities (i.e., the area formerly described by
              POSIX.2).

              **XRAT**: Informative text on the other parts of the standard.

              POSIX.1-2001 is aligned with C99, so that all of the library functions standardized in
              C99 are also standardized in POSIX.1-2001.

              The Single UNIX Specification version 3 (SUSv3) comprises the Base Specifications con‐
              taining XBD, XSH, XCU, and XRAT as above, plus X/Open Curses Issue 4 version 2  as  an
              extra volume that is not in POSIX.1-2001.

              Two  Technical Corrigenda (minor fixes and improvements) of the original 2001 standard
              have occurred: TC1 in 2003 and TC2 in 2004.

### POSIX.1-2008
       **SUSv4  **Work on the next revision of POSIX.1/SUS was completed  and  ratified  in  2008.   The
              standard is available online at ]8;;<http://www.unix.org/version4/>\<http://www.unix.org/version4/>]8;;\.

              The   changes  in  this  revision  are  not  as  large  as  those  that  occurred  for
              POSIX.1-2001/SUSv3, but a number of new interfaces are added and  various  details  of
              existing  specifications  are  modified.  Many of the interfaces that were optional in
              POSIX.1-2001 become mandatory in the 2008 revision of the standard.  A few  interfaces
              that  are  present  in POSIX.1-2001 are marked as obsolete in POSIX.1-2008, or removed
              from the standard altogether.

              The revised standard is structured in the same way as  its  predecessor.   The  Single
              UNIX Specification version 4 (SUSv4) comprises the Base Specifications containing XBD,
              XSH,  XCU,  and  XRAT,  plus  X/Open  Curses Issue 7 as an extra volume that is not in
              POSIX.1-2008.

              Again there are two levels of conformance: the baseline  _POSIX_  _Conformance_,  and  _XSI_
              _Conformance_,  which  mandates an additional set of interfaces beyond those in the base
              specification.

              In general, where the STANDARDS section of a manual page lists POSIX.1-2001, it can be
              assumed that the interface also conforms to POSIX.1-2008, unless otherwise noted.

              Technical Corrigendum 1 (minor fixes and improvements) of this standard  was  released
              in 2013.

              Technical Corrigendum 2 of this standard was released in 2016.

              Further  information  can  be  found  on  the  Austin Group web site, ]8;;<http://www.opengroup.org/austin/>\<http://www.open>‐
              group.org/austin/]8;;\.

### SUSv4 2016 edition
              This is equivalent to POSIX.1-2008, with the addition of Technical Corrigenda 1 and  2
              and the XCurses specification.

### POSIX.1-2017
              This  revision of POSIX is technically identical to POSIX.1-2008 with Technical Corri‐
              genda 1 and 2 applied.

### SUSv4 2018 edition
              This is equivalent to POSIX.1-2017, with the addition of the XCurses specification.

       The interfaces documented in POSIX.1/SUS are available as  manual  pages  under  sections  0p
       (header files), 1p (commands), and 3p (functions); thus one can write "man 3p open".

## SEE ALSO
       [**getconf**(1)](https://www.chedong.com/phpMan.php/man/getconf/1/markdown),   [**confstr**(3)](https://www.chedong.com/phpMan.php/man/confstr/3/markdown),  [**pathconf**(3)](https://www.chedong.com/phpMan.php/man/pathconf/3/markdown),  [**sysconf**(3)](https://www.chedong.com/phpMan.php/man/sysconf/3/markdown),  [**attributes**(7)](https://www.chedong.com/phpMan.php/man/attributes/7/markdown),  [**feature_test_macros**(7)](https://www.chedong.com/phpMan.php/man/featuretestmacros/7/markdown),
       [**libc**(7)](https://www.chedong.com/phpMan.php/man/libc/7/markdown), [**posixoptions**(7)](https://www.chedong.com/phpMan.php/man/posixoptions/7/markdown), [**system_data_types**(7)](https://www.chedong.com/phpMan.php/man/systemdatatypes/7/markdown)

Linux man-pages 6.7                          2023-10-31                                 [_standards_(7)](https://www.chedong.com/phpMan.php/man/standards/7/markdown)