... DocBook Documents A key feature of SGML and XML markup is that you validate it. The DocBook DTD is a precise description of valid nesting, the order of elements, and their content. All DocBook documents ... com.jclark.xml.apps.Time examples\simple.xml 6. 639 The result states that it took 6. 639 seconds to parse the DTD and the document. This indicates that the document is valid. If the document is invalid, additional ... out of context start tag. In fact, they're really the same error. The problem is never caused by the missing end tag per se, rather it's caused by the fact that something following...