released on January 30, 2002. This SUS consisted of: Base Specifications, Issue 6 Base Definitions, Issue 6 System Interfaces, Issue 6 Shell and Utilities, Issue 6 Rationale (Informative) X/Open Curses, Issue 4, Version 2 and is at the core of the UNIX 03 brand. The Base Specifications are technically identical to POSIX.1-2001, which is IEEE Std 1003.1-2001. This version had 1742 programming interfaces. An authorized guide is available for the version. 2004 Edition In 2004, a new edition of the POSIX.1-2001 standard was released, incorporating two technical corrigenda. It is called IEEE Std 1003.1, 2004 Edition. Some informally call it POSIX.1-2004, but this is not an official identification. 2008: Single UNIX Specification, version 4, POSIX.1-2008 In December 2008, the Austin Group published a new major revision of SUS and POSIX. This is the Single UNIX Specification, Version 4 (SUSv4). This SUS consists of: Base Specifications, Issue 7 Base Definitions, Issue 7 System Interfaces, Issue 7 Shell and Utilities, Issue 7 Rationale, Issue 7, (Informative) X/Open Curses, Issue 7 The Base Specifications are technically identical to POSIX.1-2008, which is IEEE Std 1003.1-2008. This version had 1833 interfaces, of which 1191 were in the System Interfaces section. 2013 Edition The Technical Corrigendum 1 is mostly targeting internationalization and it introduces a role-based access model. A trademark UNIX V7 (not to be confused with V7 UNIX, the version of Research Unix from 1979) has been created to mark compliance with SUS Version 4. 2016 Edition The Technical Corrigendum 2 has been published in September 2016, leading into IEEE Std 1003.1-2008, 2016 Edition and Single UNIX Specification, Version 4, 2016 Edition. 2018 Edition, POSIX.1-2017 In January 2018, an "administrative rollup" edition was released. It incorporates Single UNIX Specification version 4 TC1 and TC2, and is technically identical to the 2016 edition. The Base Specifications are technically identical to POSIX.1-2017, which is IEEE Std 1003.1-2017. Specification SUSv3 totals some 3700 pages, which are divided into four main parts: Base Definitions (XBD) - a list of definitions and conventions used in the specifications and a list of C header files which must be provided by compliant systems. 84 header files in total are provided. Shell and Utilities (XCU) - a list of utilities and a description of the shell, sh. 160 utilities in total are specified. System Interfaces (XSH) - contains the specification of various functions which are implemented as system calls or library functions. 1123