(NOTICE: This document is not in original distribution. Original README file is README.txt (in Japanese). You can get more information at the TOPPERS officail site: http://www.toppers.jp/en/index.html)
Toyohashi Open Platform for Embedded Real-Time Systems / Advanced Standard Profile Kernel
The TOPPERS/ASP kernel (hereinafter ASP kernel) is the foundation for the new generation of TOPPERS real-time kernels that follow the TOPPERS new generation kernel specification. ASP (Advanced Standard Profile) has been developed - as it name suggests - by extending and improving TOPPERS/JSP, a real-time kernel based on the standard profile of μITRON4.0.
You can use ASP kernel under the TOPPERS License Agreement (http://www.toppers.jp/en/license.html).
TOPPERS License Agreement is below.
Copyright (C) <Year> by <Copyright Holder 1>
Copyright (C) <Year> by <Copyright Holder 2>
...
The above copyright holders grant permission gratis to use,
duplicate, modify, or redistribute (hereafter called use) this
software (including the one made by modifying this software),
provided that the following four conditions (1) through (4) are
satisfied.
(1) When this software is used in the form of source code, the above
copyright notice, this use conditions, and the disclaimer shown
below must be retained in the source code without modification.
(2) When this software is redistributed in the forms usable for the
development of other software, such as in library form, the above
copyright notice, this use conditions, and the disclaimer shown
below must be shown without modification in the document provided
with the redistributed software, such as the user manual.
(3) When this software is redistributed in the forms unusable for the
development of other software, such as the case when the software
is embedded in a piece of equipment, either of the following two
conditions must be satisfied:
(a) The above copyright notice, this use conditions, and the
disclaimer shown below must be shown without modification in
the document provided with the redistributed software, such as
the user manual.
(b) How the software is to be redistributed must be reported to the
TOPPERS Project according to the procedure described
separately.
(4) The above copyright holders and the TOPPERS Project are exempt
from responsibility for any type of damage directly or indirectly
caused from the use of this software and are indemnified by any
users or end users of this software from any and all causes of
action whatsoever.
THIS SOFTWARE IS PROVIDED "AS IS." THE ABOVE COPYRIGHT HOLDERS AND
THE TOPPERS PROJECT DISCLAIM ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, ITS APPLICABILITY TO A PARTICULAR
PURPOSE. IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS AND THE
TOPPERS PROJECT BE LIABLE FOR ANY TYPE OF DAMAGE DIRECTLY OR
INDIRECTLY CAUSED FROM THE USE OF THIS SOFTWARE.
In short, TOPPERS License is BSD-like license with 'reporting option.' In the term (3)-(b), you can redistribute your (forked) version without the original copyright notice.