A call for open source DTDs

Elliotte Rusty Harold elharo at sunsite.unc.edu
Thu Oct 15 17:24:07 BST 1998

Let me elaborate a little on the problem.  Let us suppose we have a DTD for
plumbing. This DTD is copyright 1998 International Plumbers Association.
Can I legally place the DTD is an XML document of my own creation? The
answer is no. That would be the same as including an entire poem or other
work in my document rather than quoting a part of it.

Can I place the DTD in a separate file on my web server and reference it
like this:

<!DOCTYPE document SYSTEM "http://sunsite.unc.edu/xml/plumbing.dtd">

Again, legally, the answer is no. I cannot legally place the copyrighted
document on my server any more than I can copy a copyrighted HTML file from
another web site onto my own.

I can, however, do this:

<!DOCTYPE document SYSTEM "http://www.iap.org/xml/plumbing.dtd">

This relies on the International Association of Plumburs not changing the
URL of the plumbing DTD, not changing the DTD itself, and maintaining a web
server that's fast and accessible independently of the state of my web
server. And it completely fails for offline documents.  So this isn't a
good solution.

Is open source a solution? Maybe, especially if the DTD is external to the
document. However, standard open source licenses like the GPL are
problematic because they would seem to imply that if the DTD is included
with the document itself, then the entire document must be open source.
They are one file, after all. Not even Richard Stallman tries to make all
programs compiled with gcc, open source. Neither should using an open
source DTD taint the document the DTD validates. So if we want open source
we need a new kind of open source license that's clearer about the
distinction between DTDs and documents, even though they may be present in
the same file.

The simplest solution is to simply declare that the DTD is in the public
domain.   This works well with existing systems and allows anyone to use
the DTD any way they need to.  The only potential downside I see to this is
that there may be some standardization problems if people are allowed to
change the DTD willy-nilly. Long-term I suspect we'll develop some standard
licensing language that allows unlimited reuse, but only if the name is
changed, perhaps something like Perl's artistic license where you can do
anything you want with it as long as you don't call it Perl.

In any case, the main thing I want to bring up is to make sure DTD authors
think about these things when writing copyright statements.  If people are
going to use your DTD, they absolutely must be able to republish it.
Without special permission, standard copyright prevents that.

| Elliotte Rusty Harold | elharo at sunsite.unc.edu | Writer/Programmer |
|        XML: Extensible Markup Language (IDG Books 1998)            |
|   http://www.amazon.com/exec/obidos/ISBN=0764531999/cafeaulaitA/   |
|  Read Cafe au Lait for Java News:  http://sunsite.unc.edu/javafaq/ |
|  Read Cafe con Leche for XML News: http://sunsite.unc.edu/xml/     |

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