SAX for Pascal provides a specification, in the form of a set of Delphi interfaces, for parsing XML documents. Your client code receives a bunch of events that tell you the contents of the XML document. The main interface a SAX parser provides is IXMLReader (in the SAX.pas unit).
This interface allows an application to set and query features and properties in the parser, to register event handlers for document processing, and to initiate a document parse.
SAX is the Simple API for XML, originally a Java-only API. SAX was the first widely adopted API for XML in Java, and is a de facto standard.SAX for Pascal is the port of SAX to Borland Delphi. This is the the Delphi way to parse XML documents using SAX