to standardize the internal structures of Linux-based systems for increased compatibility. It is based on the POSIX specifications, the Single UNIX Specification, and other open standards, and also extends them in several areas; but there are some conflicts between the LSB and the POSIX standards. Few Linux distributions actually go through certification as LSB compliant. Darwin, the open source subset of macOS, has behavior that can be set to comply with UNIX 03. FreeBSD previously had a "C99 and POSIX Conformance Project" which aimed for compliance with a subset of the Single UNIX Specification, and documentation where there were differences. FreeBSD pax command does not support pax file format and thereby fails POSIX.1-2001. FreeBSD man pages sometimes indicate deviations from POSIX and thus SUS in their STANDARDS sections. OpenBSD man pages sometimes indicate deviations from POSIX and thus SUS in their STANDARDS sections. MINIX pax command does not support pax file format and thereby fails POSIX.1-2001. See also List of Unix commands Unix wars Functional specification UNIX manual Open system (computing) Open standard POSIX References External links The Single UNIX Specification, unix.org Single UNIX Specification, Version 1 X/Open CAE Specification System Interface Definitions, Issue 4, Version 2, 1994, opengroup.org X/Open CAE Specification System Interfaces and Headers, Issue 4, Version 2, 1994, opengroup.org X/Open CAE Specification Commands and Utilities, Issue 4, Version 2, 1994, opengroup.org X/Open CAE Specification Networking Services, Issue 4, 1994, opengroup.org Single UNIX® Specification, Version 1 Document Set (UNIX 95), opengroup.org – requires login to download The Single UNIX Specification, Version 2, 1997, opengroup.org The Open Group Base Specifications Issue 6, 2004, opengroup.org The Open Group Base Specifications Issue 7, 2008 edition, opengroup.org The Open Group Base Specifications Issue 7, 2013 edition, opengroup.org The Open Group Base Specifications Issue 7, 2016 edition, opengroup.org The Open Group Base Specifications Issue 7, 2018 edition, opengroup.org The Open Group Base Specifications Issue 7, opengroup.org – latest edition Single UNIX Specification, Version 4, 2018 Edition, opengroup.org X/Open Curses, Issue 4, Version 2, 1996, opengroup.org X/Open Curses, Issue 7, 2009, opengroup.org POSIX Technical Corrigendum 1, 1003.1-2001/Cor 1-2001, opengroup.org Single UNIX Specification, Version 4 Technical Corrigendum No. 1, IEEE Std 1003.1-2008/Cor 1-2013, opengroup.org Single UNIX Specification, Version 4 Technical Corrigendum No. 2, IEEE Std 1003.1-2008/Cor 2-2016, opengroup.org IEEE standards Open Group standards POSIX Unix standards