A DTD is an SGML-compliant or XML-compliant (it's written according
to the SGML or XML standard) set of rules for marking text content. It specifies
that every time
I mean that the word "Xanadu" is from a poem (not a song by Olivia Newton-John),
I will write ' DTD's can be made by anyone for any purpose. Getting everyone to agree on these,
however, is at times hard, also new discoveries can't be tagged until all agree--
EXCEPT with XML, where tags can continally be added to DTD's for individual or
group use. It's like getting everyone to speak Esperanto. In
addition, a DTD just says how I want to identify content, not how it looks.
To determine how it looks, I have to write a DSL.
(Document Style Language) file, which says--in effect--any time I start a new
chapter, center it, put it in bold, and font size such and such.
Scholars made a DTD called TEI (Text Encoding Initiative), but--sort of like a
Microsoft product--it's huge, it tries to do too much for too many people,
and ultimately fails to be efficient. Archivists have "EAD-ML" and so on.
This is all well and good if a bunch of folks agree, but that still doesn't
solve finding software to read it.
XML solves this.