XML or SGML or …

  • DocBook was historically an SGML DTD.

  • DocBook V4.x is

    • An XML or SGML DTD

    • Has an unofficial RELAX NG Grammar

    • Has an unofficial W3C XML Schema

  • DocBook V5.x is

    • A RELAX NG Grammar

    • Has a non-normative XML DTD

    • Has a non-normative W3C XML Schema