1. SGML DTD for authors of technical documentation DocBook is an SGML vocabulary particularly well suited to books and papers about computer hardware and software (though it is by no means limited to these applications). It has emerged as an open, standard DTD in the software industry, and is used to document many free software projects. This package contains the SGML DTD for DocBook, which describes the formal structure of documents complying this format. If you wish to author XML documents, see the 'docbook-xml' package. It is a part of Debian's SGML/XML infrastructure, along with other DTDs, tools for parsing, validating, and styling, and formatting SGML and XML documents. This package includes the 2.4.1, 3.0, 3.1, 4.0, and 4.1 versions of the DocBook SGML DTD. From Debian 3.0r0 APT