1STANDARDS(7)               Linux Programmer's Manual              STANDARDS(7)
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NAME

6       standards - C and UNIX Standards
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DESCRIPTION

9       The  CONFORMING TO section that appears in many manual pages identifies
10       various standards to which the documented interface conforms.  The fol‐
11       lowing list briefly describes these standards.
12
13       V7     Version 7, the ancestral UNIX from Bell Labs.
14
15       4.2BSD This is an implementation standard defined by the 4.2 release of
16              the Berkeley Software Distribution, released by  the  University
17              of  California at Berkeley.  This was the first Berkeley release
18              that contained a TCP/IP stack and the sockets API.   4.2BSD  was
19              released in 1983.
20
21              Earlier  major  BSD  releases included 3BSD (1980), 4BSD (1980),
22              and 4.1BSD (1981).
23
24       4.3BSD The successor to 4.2BSD, released in 1986.
25
26       4.4BSD The successor to 4.3BSD, released in 1993.  This  was  the  last
27              major Berkeley release.
28
29       System V
30              This  is  an implementation standard defined by AT&T's milestone
31              1983 release of its commercial System  V  (five)  release.   The
32              previous major AT&T release was System III, released in 1981.
33
34       System V release 2 (SVr2)
35              This  was the next System V release, made in 1985.  The SVr2 was
36              formally described in the System V Interface Definition  version
37              1 (SVID 1) published in 1985.
38
39       System V release 3 (SVr3)
40              This  was the successor to SVr2, released in 1986.  This release
41              was formally described in the System V Interface Definition ver‐
42              sion 2 (SVID 2).
43
44       System V release 4 (SVr4)
45              This  was the successor to SVr3, released in 1989.  This version
46              of System V is described in the "Programmer's Reference  Manual:
47              Operating  System  API  (Intel processors)" (Prentice-Hall 1992,
48              ISBN 0-13-951294-2) This release was formally described  in  the
49              System V Interface Definition version 3 (SVID 3), and is consid‐
50              ered the definitive System V release.
51
52       SVID 4 System V Interface Definition version 4, issued in 1995.  Avail‐
53              able online at http://www.sco.com/developers/devspecs/ .
54
55       C89    This was the first C language standard, ratified by ANSI (Ameri‐
56              can National Standards Institute) in 1989 (X3.159-1989).   Some‐
57              times  this  is  known  as ANSI C, but since C99 is also an ANSI
58              standard, this term is ambiguous.  This standard was also  rati‐
59              fied  by  ISO  (International  Standards  Organization)  in 1990
60              (ISO/IEC 9899:1990), and is thus occasionally referred to as ISO
61              C90.
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63       C99    This  revision of the C language standard was ratified by ISO in
64              1999 (ISO/IEC 9899:1999).  Available online at  http://www.open-
65              std.org/jtc1/sc22/wg14/www/standards.
66
67       POSIX.1-1990
68              "Portable  Operating  System  Interface  for  Computing Environ‐
69              ments".  IEEE 1003.1-1990  part  1,  ratified  by  ISO  in  1990
70              (ISO/IEC  9945-1:1990).   The term "POSIX" was coined by Richard
71              Stallman.
72
73       POSIX.2
74              IEEE Std 1003.2-1992, describing commands and  utilities,  rati‐
75              fied by ISO in 1993 (ISO/IEC 9945-2:1993).
76
77       POSIX.1b (formerly known as POSIX.4)
78              IEEE Std 1003.1b-1993 describing real-time facilities for porta‐
79              ble  operating  systems,  ratified  by  ISO  in  1996   (ISO/IEC
80              9945-1:1996).
81
82       POSIX.1c
83              IEEE Std 1003.1c-1995 describing the POSIX threads interfaces.
84
85       POSIX.1d
86              IEEE  Std  1003.1c-1999  describing  additional real-time exten‐
87              sions.
88
89       POSIX.1g
90              IEEE Std  1003.1g-2000  describing  networking  APIs  (including
91              sockets).
92
93       POSIX.1j
94              IEEE Std 1003.1j-2000 describing advanced real-time extensions.
95
96       POSIX.1-1996
97              A  1996  revision  of  POSIX.1  which  incorporated POSIX.1b and
98              POSIX.1c.
99
100       XPG3   Released in 1989, this was the first significant release of  the
101              X/Open Portability Guide, produced by the X/Open Company, a mul‐
102              tivendor consortium.  This multivolume guide was  based  on  the
103              POSIX standards.
104
105       XPG4   A revision of the X/Open Portability Guide, released in 1992.
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107       XPG4v2 A 1994 revision of XPG4.  This is also referred to as Spec 1170,
108              where 1170 referred to the number of interfaces defined by  this
109              standard.
110
111       SUS (SUSv1)
112              Single UNIX Specification.  This was a repackaging of XPG4v2 and
113              other X/Open standards (X/Open Curses Issue 4 version 2,  X/Open
114              Networking  Service  (XNS) Issue 4).  Systems conforming to this
115              standard can be branded UNIX 95.
116
117       SUSv2  Single UNIX Specification version 2.  Sometimes also referred to
118              as XPG5.  This standard appeared in 1997.  Systems conforming to
119              this standard can be branded UNIX 98.  See also http://www.UNIX-
120              systems.org/version2/ .)
121
122       POSIX.1-2001, SUSv3
123              This  was  a  2001  revision  and  consolidation of the POSIX.1,
124              POSIX.2, and SUS standards into  a  single  document,  conducted
125              under   the  auspices  of  the  Austin  group  (http://www.open
126              group.org/austin/  .)   The  standard  is  available  online  at
127              http://www.unix-systems.org/version3/  , and the interfaces that
128              it describes are also available in the Linux manual pages  pack‐
129              age under sections 1p and 3p (e.g., "man 3p open").
130
131              The  standard  defines  two levels of conformance: POSIX confor‐
132              mance, which is a baseline set of interfaces required of a  con‐
133              forming system; and XSI Conformance, which additionally mandates
134              a set  of  interfaces  (the  "XSI  extension")  which  are  only
135              optional  for  POSIX conformance.  XSI-conformant systems can be
136              branded UNIX 03.  (XSI conformance constitutes the  Single  UNIX
137              Specification version 3 (SUSv3).)
138
139              The POSIX.1-2001 document is broken into four parts:
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141              XBD:  Definitions,  terms  and  concepts, header file specifica‐
142              tions.
143
144              XSH: Specifications of functions (i.e., system calls and library
145              functions in actual implementations).
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147              XCU:  Specifications  of  commands and utilities (i.e., the area
148              formerly described by POSIX.2).
149
150              XRAT: Informative text on the other parts of the standard.
151
152              POSIX.1-2001 is aligned with C99, so that  all  of  the  library
153              functions   standardized   in   C99  are  also  standardized  in
154              POSIX.1-2001.
155
156              Two Technical Corrigenda (minor fixes and improvements)  of  the
157              original  2001  standard have occurred: TC1 in 2003 (referred to
158              as POSIX.1-2003), and TC2 in 2004 (referred to as POSIX.1-2004).
159
160       POSIX.1-2008, SUSv4
161              Work on the next revision of POSIX.1/SUS was completed and rati‐
162              fied in 2008.
163
164              The  changes  in  this  revision  are not as large as those that
165              occurred for POSIX.1-2001/SUSv3, but a number of new  interfaces
166              are  added  and  various  details of existing specifications are
167              modified.   Many  of  the  interfaces  that  were  optional   in
168              POSIX.1-2001  become mandatory in the 2008 revision of the stan‐
169              dard.  A few interfaces that are  present  in  POSIX.1-2001  are
170              marked as obsolete in POSIX.1-2008, or removed from the standard
171              altogether.
172
173              The revised standard is broken  into  the  same  four  parts  as
174              POSIX.1-2001, and again there are two levels of conformance: the
175              baseline POSIX Conformance, and XSI Conformance, which  mandates
176              an  additional set of interfaces beyond those in the base speci‐
177              fication.
178
179              In general, where the CONFORMING TO section  of  a  manual  page
180              lists  POSIX.1-2001,  it  can be assumed that the interface also
181              conforms to POSIX.1-2008, unless otherwise noted.
182
183              Further information can be found on the Austin group  web  site,
184              http://www.opengroup.org/austin/ .
185

SEE ALSO

187       feature_test_macros(7), libc(7), posixoptions(7)
188

COLOPHON

190       This  page  is  part of release 3.25 of the Linux man-pages project.  A
191       description of the project, and information about reporting  bugs,  can
192       be found at http://www.kernel.org/doc/man-pages/.
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196Linux                             2009-06-01                      STANDARDS(7)
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