Markdown licensing

[John Gruber]

european bob <bob at wolfwall.com> wrote on 12/13/04 at 9:32am:

> (First thought is; is this change for change's sake? Or is there
> actually some evidence people need a licence change?)

I've received a handful of emails from people working on non-GPL
open source projects who would like to include Markdown.pl -- or PHP
Markdown, which is also GPL'd because it's derived from the original
-- with their projects, but feel they can't because of licensing
issues. Most of these projects are BSD-licensed.

I've thought about this a lot, and I've come to the conclusion that
the GPL and LGPL were written with the C family of programming
languages in mind. E.g. their talk of "linking" a library as part of
a greater whole. How does that apply to dynamic scripting languages
such as Perl and PHP?

I am not a lawyer. But I'd argue along the lines of what you're
saying, Bob -- that calling out to the shell to run Markdown.pl is
effectively using it as a standalone separate process. Hence, for
this reason, I've granted free use of Markdown.pl to commercial
weblog editing apps such as Ecto and MarsEdit. 

With PHP, however, it's a little different. Because what you do
there is `include()` markdown.php, and then call Markdown(). I can
see why people would feel that if their own projects are
BSD-licensed, they can't use a GPL'd PHP-Markdown in this context.

And at some point I ought to get around to turning my Perl version
into a proper CPAN module, at which point single-licensing under the
GPL might really get in the way for some people. In fact, my other
inkling is to license Markdown.pl under the same terms as Perl
itself -- dual-licensed as "your choice" between the GPL and the
Artistic License. Which is how most CPAN modules are licensed.

Cf.: <http://www.theoretic.com/ArtisticLicenses/PAL>

That would free up people who feel they can't use it under the GPL,
but it opens the can of worms regarding the somewhat vague nature of
certain passages in the Artistic License.


> While I don't really care for licences which attempt to 'regulate'
> modification in the way (for example) the Sun Java license does, I can
> see there being some need for 'regulation' of the file format. It
> wouldn't be good for Markdown to become the new wiki-syntax, with
> everyone adding their own bits of syntax for special things and
> overriding existing syntax. I would think that the GPL would give
> greater scope for unification if alternate modifications did become
> popular.

I've been wondering about that, too. Thinking that perhaps I should
"release" the syntax specification/documention under its own
license. The idea being that I'd like to make the syntax freely
available to anyone who wants to implement it, but if they want to
call it "Markdown", they can't change it.


> PS. While I don't see the need to change from GPL to BSD, if you must
> please make sure you use a BSD licence that actually is a free software
> licence too - not all of them are, and it's usually a mistake to say
> "BSD licence". 

I grabbed the "BSD" license used with SmartyPants from OSI's web site:

<http://www.opensource.org/licenses/bsd-license.php>

-J.G.