SSAX is an XML & SXML processing library in quite portable Scheme.

(From the website)

SSAX is a full-featured, algorithmically optimal, pure-functional parser, which can act as a stream processor. SSAX is an efficient SAX parser that is easy to use. SSAX minimizes the amount of application-specific state that has to be shared among user-supplied event handlers. SSAX makes the maintenance of an application-specific element stack unnecessary, which eliminates several classes of common bugs. SSAX is written in a pure-functional subset of Scheme. Therefore, the event handlers are referentially transparent, which makes them easier for a programmer to write and to reason about. The more expressive, reliable and easier to use application interface for the event-driven XML parsing is the outcome of implementing the parsing engine as an enhanced tree fold combinator, which fully captures the control pattern of the depth-first tree traversal.

SXML is an abstract syntax tree of an XML document. SXML is also a concrete representation of the XML Infoset in the form of S-expressions.

SXSLT? is a manipulation language for XML and SXPath is an XPath-conforming XML query language. Both languages internally rely on SXML as a representation of the XML Infoset.

SXML-example is a example of SXML. Basically the html file of this website was downloaded ( Then it was parsed using SSAX which outputs an SXML file that is equal to the XML that was parsed but instead uses the SXML format.