The UNIX system family tree
                                     -------------------------------------------------------------------------------

                                                                First Edition (V1)
                                                                      |
                                                                Second Edition (V2)
                                                                      |
                                                                Third Edition (V3)
                                                                      |
                                                                Fourth Edition (V4)
                                                                      |
                                                                Fifth Edition (V5)
                                                                      |
                                                                Sixth Edition (V6) ---------------------*
                                                                     / \                                |
                                                                    /   \                               |
                                                                   /     \                              |
                                                                Seventh Edition (V7)                    |
                                                                 /          \                           |
                                                                /            \                        1BSD
                                         SYSTEM I--------------*              *--------------32V        |
                                            |                                                  \      2BSD---------------*
                                         SYSTEM II                                              \    /                   |
                                            |                                                    \  /                    |
                                         SYSTEM III                                               \/                     |
                                            |                                                    3BSD                    |
                                         SYSTEM IV                                                |                      |
                                            |                           ...................... 4.0BSD               2.7.9BSD
                Mach 2 <---------------- SYSTEM V                       .                         |                      |
                  |                         |    \                   Sun OS 1                  4.1BSD --------------> 2.8BSD
                Mach 2.5                   SVR I  \                     .                         |                      |
(SCO/MS)          |                         |      \                    .                     4.1aBSD -----------\       |
  |               |                       SVR II    OSF/2        ....Sun OS 4.x                   |                \     |
XENIX 1.0         |                         |           |        .                            4.1bBSD                \   |
  |               |                       SVR III       |        .                                |                    \ |
XENIX 2.0         |                      /  |           |        .                    *------ 4.1cBSD --------------> 2.9BSD
  |               |                     /   |           |        X                   /            |                      |
SCO SVR 3.2 <-----|---+--------> SVR 3.2    |           |        .              Eighth Edition    |                   2.9BSD-Seismo
  |               |   |            |        |           |        .                   |            |                      |
SCO OpenDesktop 2 |   +------------+--> AT&T SVR 4 <----|----------------------------+----<--- 4.2BSD               2.9.1BSD
  |               |                |        |           |        .                   |            |                      |
SCO OpenDesktop 3 |                |        +           |        .                   +----<--- 4.3BSD -------------> 2.10BSD
  |               |       +--------|-----SVR 4.2----+---|--------+                   |            |                /     |
  |               |       |        |        +       |   |        |                   |            |               /      |
SCO OpenServer 5  |   Unixware2   AIX 3     |       |   |    Solaris 2          Ninth Edition     |              / 2.10.1BSD
  |               |   (Novell)   (IBM)      |       |   |        |                   |         4.3BSD Tahoe-----+        |
  |               |       |        |        O       |   |    Solaris 2.x             |            |              \       |
  |               |       |        |        t       |   |        |                   |            |                \     |
  |               |   Unixware 7  AIX 4     h       |   |    Solaris 7               v            |                  2.11BSD
  |               |     (SCO)      |        e       |   |        |              Tenth Edition     |                      |
  |               |       |        |        r       |   |    Solaris 8                            |                  2.11BSD rev #430
  |               |    (SVR 5)     |        |       |   |        |                             4.3BSD NET/1              |
  |               |       |        |        &       |   |   Solaris 9EA                           |                      v
  |---------------|----Unixware 8  |                |   |        |                             4.3BSD Reno
  |               |       |        |                |   |        V                                |
OpenServer 5.06   |       V        |                |   V                         /*---------- 4.3BSD NET/2 -------------------+-------------*
  |               |                |                | Ultrix 4 <.................* |                    |                      |             |
  |               |              AIX 4.3.3          |  (DEC)                    386BSD 0.0              |                      |           BSD/386 ALPHA
  V               |                |                |   |                         |                     |                      |             |
                  |                |                | Tru 64 5.x                386BSD 0.1 ------------>+                      |           BSD/386 0.3.[13]
                  |                V                | (Compaq)--->                 |     \              |                  4.4BSD Alpha      |
                  |                                 |                              |     386BSD 1.0     |                      |           BSD/386 0.9.[34]
                  + <...............................|..............................|....................|..................4.4BSD            |
                  .                                 |   .                          |                    |                    / |             |
             Mach 3 (Base BSD)                 .....|.............                 |                    |   4.4BSD-Encumbered  |             |
                  .                            .    |            .                 |                 NetBSD 0.8                |           BSD/386 1.0
                  .                         HP-UX 8 |          IRIX 4.x            |                    |                      |             |
                  .                         ( HP )  |          (SGI)            FreeBSD 1.0          NetBSD 0.9                |           BSD/386 1.1
          ........*..........                  .    |            .                 |                    |           .----- 4.4BSD Lite       |
          .                 .                  .    |            .              FreeBSD 1.1             |          /   /       |     \       |
    Gnu Hurd 0.1          NeXT              HP-UX 9 |          IRIX 5.x            |                    |         /   /        |      \      |
          .                 .                  .    |            .              FreeBSD 1.1.5       .---|--------'   /         |       \     |
          .                 @                  .    |            .                 |               /    |           /          |        \    |
          .                                    + <- + ---------> +              FreeBSD 1.1.5.1   /     |          /           |         \   |
    Gnu Hurd 0.2                               |                 |                 |             /   NetBSD 1.0 <-'            |          \  |
          .                                 HP-UX 10.x         IRIX 6.0            |            /       |                      |           \ |
          .                                    |                 |              FreeBSD 2.0 <--'        |                      |           BSD/OS 2.0
    Gnu Hurd (H2)                              |                 |                 |                     \                     |             |
          .                                 HP-UX 11.x         IRIX 6.5.15      FreeBSD 2.0.5             \                    |           BSD/OS 2.0.1
          .                                    |                 |                 |                 .-----\------------- 4.4BSD Lite2       |
          .                                    |                 |                 |                 |      \             |  |   |   |       |
          V                                    V                 V                 |                 | .-----|------Rhapsody |   |   |       |
                                                                                   |                 | |     |        NetBSD 1.3 |   |       |
                                                                                   |                 | |     |           OpenBSD 2.3 |       |
                                                                                   |                 | |     |                BSD/OS 3.0     |
                                                                                FreeBSD 2.1          | |     |                               |
                                                                                 |   |               | |  NetBSD 1.1 ------.               BSD/OS 2.1
                                                                                 | FreeBSD 2.1.5     | |     |              \                |
                                                                                 |     |             | |  NetBSD 1.2         \             BSD/OS 3.0
                                                                                 | FreeBSD 2.1.6     | |     |  \          OpenBSD 2.0       |
                                                                                 |     |             | |     |   \             |             |
                                                                                 | FreeBSD 2.1.6.1   | |     |    \            |             |
                                                                                 |     |             | |     |     \           |             |
                                                                                 | FreeBSD 2.1.7     | |     |      |          |             |
                                                                                 |     |             | |     |  NetBSD 1.2.1   |             |
                                                                                 | FreeBSD 2.1.7.1   | |     |                 |             |
                                                                                 |                   | |     |                 |             |
                                                                                 |                   | |     |                 |             |
                                                                                 *-FreeBSD 2.2       | |     |                 |             |
                                                                                 |        \          | |     |                 |             |
                                                                                 |     FreeBSD 2.2.1 | |     |                 |             |
                                                                                 |         |         | |     |                 |             |
                                                                                 |     FreeBSD 2.2.2 | |     |             OpenBSD 2.1       |
                                                                                 |         |         | |     |                 |             |
                                                                                 |     FreeBSD 2.2.5 | |     |                 |             |
                                                                                 |         |         | |     |             OpenBSD 2.2       |
                                                                                 |         |         | |  NetBSD 1.3           |             |
                                                                                 |     FreeBSD 2.2.6 | |     |    |            |             |
                                                                                 |         |         | |     | NetBSD 1.3.1    |           BSD/OS 3.1
                                                                                 |         |         | |     |    |        OpenBSD 2.3       |
                                                                                 |         |         | |     | NetBSD 1.3.2    |             |
                                                                                 |     FreeBSD 2.2.7 | |     |    |            |             |
                                                                                 |         |         | |     |    |            |           BSD/OS 4.0
                                                                                 |         v         | |     |    |            |             |
                                                                                 |     FreeBSD 2.2.8 | |     |    |            |             |
                                                                                 |                   | |     |    |        OpenBSD 2.4       |
                                                                                FreeBSD 3.0 <--------* |     |    v            |             |
                                                                                 |                     |     | NetBSD 1.3.3    |             |
                                                                                 *---FreeBSD 3.1       |     |                 |             |
                                                                                 |       |             |     |                 |           BSD/OS 4.0.1                               Linux 0.1
                                                                                 |   FreeBSD 3.2----*  |  NetBSD 1.4       OpenBSD 2.5       |                                             |
                                                                                 |       |          |  |  |  |    |            |             |                                             |	
                                                                                 |       |          |  |  |  |    |            |             |                                             |
                                                                                 |       |          |  |  |  |    |            |             |                                             |
                                                                                 |   FreeBSD 3.3    |  |  |  | NetBSD 1.4.1    |             |                                        Linux 1.0
                                                                                 |       |          |  |  |  |    |        OpenBSD 2.6       |                                             |     \
                                                                                 |   FreeBSD 3.4    |  |  |  |    |            |             |                                             |      \
                                                                                 |           |      |  |  |  |    |            |           BSD/OS 4.1                                 Linux 1.0.x  Linux 1.1.x 
                                                                                FreeBSD 4.0  |      |  |  |  | NetBSD 1.4.2    |             |                                             |       |
                                                                                 |           |      |  |  |  |    |            |             |                                             |       |
                                                                                 |           |      |  |  |  |    |            |             |                                             |.......+
                                                                                 |   FreeBSD 3.5    |  |  |  |    |        OpenBSD 2.7       |                                             |       .
                                                                                 |           |      |  |  |  |    |            |             |                                        Linux 1.2.x  .
                                                                                 |   FreeBSD 3.5.1  |  |  |  |    |            |             |                                             |     \ .					    
                                                                                 |                  |  |  |  |    |            |             |                                             |      \. 
                                                                                 *---FreeBSD 4.1    |  |  |  |    |            |             |                                             |       Linux 1.3.x
                                                                                 |      |           |  | (?) |    |            |             |                                             |       |
                                                                                 |   FreeBSD 4.1.1  |  |  /  |    |            |             |                                             |       |
                                                                                 |      |           |  | /   |    v            |             |                                             |.......+
                                                                                 |   FreeBSD 4.2   Darwin/   | NetBSD 1.4.3    |             |                                             |       .
                                                                                 |      |         Mac OS X   |             OpenBSD 2.8     BSD/OS 4.2                                 Linux 2.0.x  .
                                                                                 |      |           10.0  NetBSD 1.5           |             |                                             |     \ . 
                                                                                 |   FreeBSD 4.3      |      |    |            |             v                                             |      \.
                                                                                 |      |             |      |    v        OpenBSD 2.9                                                     |       Linux 2.1.x
                                                                                 |      |             |      | NetBSD 1.5.1    |                                                           |       | 
                                                                                 |      |             |      |    |            |                                                           |       |
                                                                                 |   FreeBSD 4.4      |      | NetBSD 1.5.2    |                                                           |.......+
                                                                                 |      |             |      |                 |                                                           |       . 
                                                                                 |      v             |      |                 |                                                      Linux 2.2.x  .
                                                                                 |                    |      |                 |                                                           |     \ .
                                                                                FreeBSD 5.0-current   |   NetBSD -current  OpenBSD -current                                                |      \.
                                                                                 |                    |      |                 |                                                           |       Linux 2.3.x 
                                                                                 v                    |      v                 v                                                           |       |
                                                                                                   Mac OS X                                                                           Linux 2.4.x  +	
                                                                                                     10.1                                                                                  |      \. 
                                                                                                                                                                                        2.4.17   2.5.2 	

					                 The UNIX system family tree
				-------------------------------------------------------------------------------

                                                                First Edition (V1)
                                                                      |
                                                                Second Edition (V2)
                                                                      |
                                                                Third Edition (V3)
                                                                      |
                                                                Fourth Edition (V4)
                                                                      |
                                                                Fifth Edition (V5)
                                                                      |
                                                                Sixth Edition (V6) ---------------------*
                                                                     / \                                |
                                                                    /   \                               |
                                                                   /     \                              |
                                                                Seventh Edition (V7)                    |
                                                                 /          \                           |
                                                                /            \                        1BSD
                                         SYSTEM I--------------*              *--------------32V        |
                                            |                                                  \      2BSD---------------*
                                         SYSTEM II                                              \    /                   |
                                            |                                                    \  /                    |
                                         SYSTEM III                                               \/                     |
                                            |                                                    3BSD                    |
                                         SYSTEM IV                                                |                      |
                                            |                           ...................... 4.0BSD               2.7.9BSD
                Mach 2 <---------------- SYSTEM V                       .                         |                      |
                  |                         |    \                   Sun OS 1                  4.1BSD --------------> 2.8BSD
                Mach 2.5                   SVR I  \                     .                         |                      |
(SCO/MS)          |                         |      \                    .                     4.1aBSD -----------\       |
  |               |                       SVR II    OSF/2        ....Sun OS 4.x                   |                \     |
XENIX 1.0         |                         |           |        .                            4.1bBSD                \   |
  |               |                       SVR III       |        .                                |                    \ |
XENIX 2.0         |                      /  |           |        .                    *------ 4.1cBSD --------------> 2.9BSD
  |               |                     /   |           |        X                   /            |                      |
SCO SVR 3.2 <-----|---+--------> SVR 3.2    |           |        .              Eighth Edition    |                   2.9BSD-Seismo
  |               |   |            |        |           |        .                   |            |                      |
SCO OpenDesktop 2 |   +------------+--> AT&T SVR 4 <----|----------------------------+----<--- 4.2BSD               2.9.1BSD
  |               |                |        |           |        .                   |            |                      |
SCO OpenDesktop 3 |                |        +           |        .                   +----<--- 4.3BSD -------------> 2.10BSD
  |               |       +--------|-----SVR 4.2----+---|--------+                   |            |                /     |
  |               |       |        |        +       |   |        |                   |            |               /      |
SCO OpenServer 5  |   Unixware2   AIX 3     |       |   |    Solaris 2          Ninth Edition     |              / 2.10.1BSD
  |               |   (Novell)   (IBM)      |       |   |        |                   |         4.3BSD Tahoe-----+        |
  |               |       |        |        O       |   |    Solaris 2.x             |            |              \       |
  |               |       |        |        t       |   |        |                   |            |                \     |
  |               |   Unixware 7  AIX 4     h       |   |    Solaris 7               v            |                  2.11BSD
  |               |     (SCO)      |        e       |   |        |              Tenth Edition     |                      |
  |               |       |        |        r       |   |    Solaris 8                            |                  2.11BSD rev #430
  |               |    (SVR 5)     |        |       |   |        |                             4.3BSD NET/1              |
  |               |       |        |        &       |   |   Solaris 9EA                           |                      v
  |---------------|----Unixware 8  |                |   |        |                             4.3BSD Reno
  |               |       |        |                |   |        V                                |
OpenServer 5.06   |       V        |                |   V                         /*---------- 4.3BSD NET/2 -------------------+-------------*
  |               |                |                | Ultrix 4 <.................* |                    |                      |             |
  |               |              AIX 4.3.3          |  (DEC)                    386BSD 0.0              |                      |           BSD/386 ALPHA
  V               |                |                |   |                         |                     |                      |             |
                  |                |                | Tru 64 5.x                386BSD 0.1 ------------>+                      |           BSD/386 0.3.[13]
                  |                V                | (Compaq)--->                 |     \              |                  4.4BSD Alpha      |
                  |                                 |                              |     386BSD 1.0     |                      |           BSD/386 0.9.[34]
                  + <...............................|..............................|....................|..................4.4BSD            |
                  .                                 |   .                          |                    |                    / |             |
             Mach 3 (Base BSD)                 .....|.............                 |                    |   4.4BSD-Encumbered  |             |
                  .                            .    |            .                 |                 NetBSD 0.8                |           BSD/386 1.0
                  .                         HP-UX 8 |          IRIX 4.x            |                    |                      |             |
                  .                         ( HP )  |          (SGI)            FreeBSD 1.0          NetBSD 0.9                |           BSD/386 1.1
          ........*..........                  .    |            .                 |                    |           .----- 4.4BSD Lite       |
          .                 .                  .    |            .              FreeBSD 1.1             |          /   /       |     \       |
    Gnu Hurd 0.1          NeXT              HP-UX 9 |          IRIX 5.x            |                    |         /   /        |      \      |
          .                 .                  .    |            .              FreeBSD 1.1.5       .---|--------'   /         |       \     |
          .                 @                  .    |            .                 |               /    |           /          |        \    |
          .                                    + <- + ---------> +              FreeBSD 1.1.5.1   /     |          /           |         \   |
    Gnu Hurd 0.2                               |                 |                 |             /   NetBSD 1.0 <-'            |          \  |
          .                                 HP-UX 10.x         IRIX 6.0            |            /       |                      |           \ |
          .                                    |                 |              FreeBSD 2.0 <--'        |                      |           BSD/OS 2.0
    Gnu Hurd (H2)                              |                 |                 |                     \                     |             |
          .                                 HP-UX 11.x         IRIX 6.5.15      FreeBSD 2.0.5             \                    |           BSD/OS 2.0.1
          .                                    |                 |                 |                 .-----\------------- 4.4BSD Lite2       |
          .                                    |                 |                 |                 |      \             |  |   |   |       |
          V                                    V                 V                 |                 | .-----|------Rhapsody |   |   |       |
                                                                                   |                 | |     |        NetBSD 1.3 |   |       |
                                                                                   |                 | |     |           OpenBSD 2.3 |       |
                                                                                   |                 | |     |                BSD/OS 3.0     |
                                                                                FreeBSD 2.1          | |     |                               |
                                                                                 |   |               | |  NetBSD 1.1 ------.               BSD/OS 2.1
                                                                                 | FreeBSD 2.1.5     | |     |              \                |
                                                                                 |     |             | |  NetBSD 1.2         \             BSD/OS 3.0
                                                                                 | FreeBSD 2.1.6     | |     |  \          OpenBSD 2.0       |
                                                                                 |     |             | |     |   \             |             |
                                                                                 | FreeBSD 2.1.6.1   | |     |    \            |             |
                                                                                 |     |             | |     |     \           |             |
                                                                                 | FreeBSD 2.1.7     | |     |      |          |             |
                                                                                 |     |             | |     |  NetBSD 1.2.1   |             |
                                                                                 | FreeBSD 2.1.7.1   | |     |                 |             |
                                                                                 |                   | |     |                 |             |
                                                                                 |                   | |     |                 |             |
                                                                                 *-FreeBSD 2.2       | |     |                 |             |
                                                                                 |        \          | |     |                 |             |
                                                                                 |     FreeBSD 2.2.1 | |     |                 |             |
                                                                                 |         |         | |     |                 |             |
                                                                                 |     FreeBSD 2.2.2 | |     |             OpenBSD 2.1       |
                                                                                 |         |         | |     |                 |             |
                                                                                 |     FreeBSD 2.2.5 | |     |                 |             |
                                                                                 |         |         | |     |             OpenBSD 2.2       |
                                                                                 |         |         | |  NetBSD 1.3           |             |
                                                                                 |     FreeBSD 2.2.6 | |     |    |            |             |
                                                                                 |         |         | |     | NetBSD 1.3.1    |           BSD/OS 3.1
                                                                                 |         |         | |     |    |        OpenBSD 2.3       |
                                                                                 |         |         | |     | NetBSD 1.3.2    |             |
                                                                                 |     FreeBSD 2.2.7 | |     |    |            |             |
                                                                                 |         |         | |     |    |            |           BSD/OS 4.0
                                                                                 |         v         | |     |    |            |             |
                                                                                 |     FreeBSD 2.2.8 | |     |    |            |             |
                                                                                 |                   | |     |    |        OpenBSD 2.4       |
                                                                                FreeBSD 3.0 <--------* |     |    v            |             |
                                                                                 |                     |     | NetBSD 1.3.3    |             |
                                                                                 *---FreeBSD 3.1       |     |                 |             |
                                                                                 |       |             |     |                 |           BSD/OS 4.0.1                               Linux 0.1
                                                                                 |   FreeBSD 3.2----*  |  NetBSD 1.4       OpenBSD 2.5       |                                             |
                                                                                 |       |          |  |  |  |    |            |             |                                             |	
                                                                                 |       |          |  |  |  |    |            |             |                                             |
                                                                                 |       |          |  |  |  |    |            |             |                                             |
                                                                                 |   FreeBSD 3.3    |  |  |  | NetBSD 1.4.1    |             |                                        Linux 1.0
                                                                                 |       |          |  |  |  |    |        OpenBSD 2.6       |                                             |     \
                                                                                 |   FreeBSD 3.4    |  |  |  |    |            |             |                                             |      \
                                                                                 |           |      |  |  |  |    |            |           BSD/OS 4.1                                 Linux 1.0.x  Linux 1.1.x 
                                                                                FreeBSD 4.0  |      |  |  |  | NetBSD 1.4.2    |             |                                             |       |
                                                                                 |           |      |  |  |  |    |            |             |                                             |       |
                                                                                 |           |      |  |  |  |    |            |             |                                             |.......+
                                                                                 |   FreeBSD 3.5    |  |  |  |    |        OpenBSD 2.7       |                                             |	   .
                                                                                 |           |      |  |  |  |    |            |             |                                        Linux 1.2.x  .
                                                                                 |   FreeBSD 3.5.1  |  |  |  |    |            |             |                                             |	 \ .					    
                                                                                 |                  |  |  |  |    |            |             |                                             |      \. 
                                                                                 *---FreeBSD 4.1    |  |  |  |    |            |             |                                             |       Linux 1.3.x
                                                                                 |      |           |  | (?) |    |            |             |                                             |       |
                                                                                 |   FreeBSD 4.1.1  |  |  /  |    |            |             |                                             |       |
                                                                                 |      |           |  | /   |    v            |             |                                             |.......+
                                                                                 |   FreeBSD 4.2   Darwin/   | NetBSD 1.4.3    |             |                                             |       .
                                                                                 |      |         Mac OS X   |             OpenBSD 2.8     BSD/OS 4.2                                 Linux 2.0.x  .
                                                                                 |      |           10.0  NetBSD 1.5           |             |                                             |     \ . 
                                                                                 |   FreeBSD 4.3      |      |    |            |             v                                             |      \.
                                                                                 |      |             |      |    v        OpenBSD 2.9                                                     |       Linux 2.1.x
                                                                                 |      |             |      | NetBSD 1.5.1    |                                                           |       | 
                                                                                 |      |             |      |    |            |                                                           |       |
                                                                                 |   FreeBSD 4.4      |      | NetBSD 1.5.2    |                                                           |.......+
                                                                                 |      |             |      |                 |                                                           |       . 
                                                                                 |      v             |      |                 |                                                      Linux 2.2.x  .
                                                                                 |                    |      |                 |                                                           |     \ .
                                                                                FreeBSD 5.0-current   |   NetBSD -current  OpenBSD -current                                                |      \.
                                                                                 |                    |      |                 |                                                           |       Linux 2.3.x 
                                                                                 v                    |      v                 v                                                           |       |
                                                                                                   Mac OS X                                                                           Linux 2.4.x  +	
                                                                                                     10.1                                                                                  |      \. 
                                                                                                                                                                                        2.4.17   2.5.2