カリフォルニア大学バークレー校は2月8日(米国時間)付けでオペレーティングシステム「Plan 9」のライセンスファイルを更新した。ライセンスファイルには、これまで「Lucent Public License, Version 1.02」のもとで配布されてきた「Plan 9」を「GNU General Public License, Version 2」で配布することに関してベル研究所から認可されていると説明がある。ライセンスファイルにはGPLv2が記載されている。

The University of California, Berkeley, has been authorised by
Alcatel-Lucent to release all Plan 9 software previously governed by
the Lucent Public License, Version 1.02 under the GNU General
Public License, Version 2.

You can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation;
version 2 of the License.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA

The Plan 9 software is provided under the terms of the
Lucent Public License, Version 1.02, reproduced below,
with the following notable exceptions:

1. No right is granted to create derivative works of or
   to redistribute (other than with the Plan 9 Operating System)
   the screen imprinter fonts identified in subdirectory
   /lib/font/bit/lucida and printer fonts (Lucida Sans Unicode, Lucida
   Sans Italic, Lucida Sans Demibold, Lucida Typewriter, Lucida Sans
   Typewriter83), identified in subdirectory /sys/lib/postscript/font.
   These directories contain material copyrights by B&H Inc. and Y&Y Inc.

2. The printer fonts identified in subdirectory /sys/lib/ghostscript/font
   are subject to the GNU GPL, reproduced in the file /LICENSE.gpl.

3. The ghostscript program in the subdirectory /sys/src/cmd/gs is
   covered by the Aladdin Free Public License, reproduced in the file
   /LICENSE.afpl.

Other, less notable exceptions are marked in the file tree with
COPYING, COPYRIGHT, or LICENSE files.
http://akaros.cs.berkeley.edu/files/Plan9Licenseより抜粋

「Plan 9」は研究開発で活用されることが多いオペレーティングシステム。今回GPLv2での配布へ切り替わったことで、これまでLinuxが採用されてきたシーンでも注目を集める可能性がある。