9.1 Introduction

This suite of packages consists of the sgml package, which can parse XML, HTML, XHTML, and even SGML documents and the xpath package, which supports XPath queries on XML documents. The sgml package is an adaptation of a similar package in SWI Prolog and a port of SWI's codebase with some minor changes. The xpath package provides an interface to the popular libxml2 library, which supports XPath and XML parsing, and is used in Mozilla based browsers. At present, the XML parsing capabilities of libxml2 are not utilized explicitly in XSB, but such support might be provided in the future. The sgml package does not rely on libxml2 ^9.1.