[License-discuss] MIT license difference between X.org, SPDX and OSI

Sebastian Crane seabass-labrax at gmx.com
Sat Jun 12 21:08:00 UTC 2021

Dear Keith,

I came across your email whilst browsing the archives for this mailing
list. Hopefully this message might still be useful to you despite the
somewhat delayed response! :)

On Sun, Mar 21, 2021 at 05:09:14PM -0700, Keith Packard wrote:
> We were happily reviewing a licensing update in some X.org code and
> came across a discrepancy between the 'MIT' license as published on
> opensource.org and the current best-practices 'MIT' license as used by
> X.org projects and as described by the SPDX license text.
> ...
> The parenthetical clause, ?(including the next paragraph),? was added
> as a result of discussions between various stakeholders as referenced
> here:
> 	https://lists.x.org/archives/xorg/2007-July/026300.html

Automatic license checkers that follow the SPDX License List Matching
Guidelines ( https://spdx.dev/license-list/matching-guidelines ) should
identify both the X.org and the OSI variant as 'MIT', because the markup
for the MIT license in the source repository has the extra clause
wrapped in an <optional> tag:


	<p>The above copyright notice and this permission notice
	<optional>(including the next paragraph)</optional>shall be
	included in all copies or substantial portions of the

That is, what SPDX calls the 'MIT' license is intended to describe both
of the variants that you quoted, although other variants that differ
more substantially have their own SPDX identifiers.

Granted, it is a larger difference that the optional tag is usually used
for; it is more often employed for marking minor formatting such as
bullet points and numbering. As the inclusion of this clause predates my
involvement with SPDX, I can only provide a GitHub issue for context of
the decision to use <optional> for that clause!


I hope I've been able to provide some clarification on this. Please feel
free to respond (either on-list or personally) if you have any other
questions about SPDX, and I shall endeavour to answer them!

Best wishes,


PS. Keep up the great work with X.org! I found your recent interview on
the FLOSS Weekly podcast very inspirational.

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