[License-review] Legacy Approval, Licnese of Jam

[Jack Hill]

As a licensee of Jam, I'm asking for legacy approval of the following 
terms:

"""
License is hereby granted to use this software and distribute it
freely, as long as this copyright notice is retained and modifications
are clearly marked.

ALL WARRANTIES ARE HEREBY DISCLAIMED.
"""

This is the license used by Jam [0] and its forks [1][2][3] (n.b. the 
boost version is also distributed under the Boost license). Outside of 
Boost, I don't believe this build tool is widely used. However, it is 
needed to build at least one important open source package: the Argyll 
Color Management System. Argyll is the only open source package that I 
know of that can generate color calibration profiles, so it is critically 
important for the use of open source software in fields where that is 
important.

I believe that the proliferation category for this license is 
Other/Miscellaneous.

In other discussions [4] I've had about this license, the problematic 
points were what "distribute freely" meant, and how modifications could be 
clearly marked. The Argyll fork of Jam marks modifications as follows:

"""
This if "Argyll-Jam", a simple derivative of the "FT-Jam" build tool, based and
100% compatible with Jam 2.5. See http://www.freetype.org/jam/ for more
details about FT-Jam.

This is the "FT-Jam" 2.5.2 release, with minor ArgyllCMS tweaks,
and the ArgyllCMS V1.3.3 Jambase as the default rule set.

Note that you'll find the original Jam README in the file README.ORG
"""

[0] https://www.perforce.com/documentation/jam-documentation
[1] https://www.freetype.org/jam/index.html
[2] http://www.argyllcms.com/doc/Compiling.html
[3] https://www.boost.org/doc/libs/1_76_0/tools/build/doc/html/index.html#bbv2.jam
[4] https://lists.gnu.org/archive/html/guix-devel/2021-04/msg00436.html

Best,
Jack