.NET & XML

Reading a PYX Document

Before you can write an XmlPyxReader, you first need to understand PYX syntax. PYX is a line-oriented XML syntax, developed by Sean McGrath, which reflects XML’s SGML heritage. PYX is based on Element Structure Information Set (ESIS), a popular alternative syntax for SGML.

Tip

Unlike many of the terms in this book, PYX is not an acronym for anything. A pyx is is a container used in certain religious rites, and the PYX notation was developed mostly using the Python programming language.

In a line-oriented format, each XML node occurs on a new line. The XML nodes that PYX can represent include start element, end element, attribute, character data, and processing instruction. The first character of each line indicates what sort of node the line represents. Table 4-1 shows the prefix characters and what node type each represents.

Table 4-1. PYX prefix characters and their corresponding XmlNodeType values

PYX prefix character	XmlNodeType value
(	Element
)	EndElement
A	Attribute
-	Text
?	ProcessingInstruction

As you can see by the limited number of node types it contains, PYX represents only the logical structure of an XML document, not the physical structure. There are no DocumentType, EntityReference, Comment, or CDATA XmlNodeTypes in a PYX document. This lack of certain nodes is consistent with PYX’s ESIS ancestry; in SGML, the separation between document structure and document content is enforced more rigidly than in ...