Member Submission - Note

Date: Nov. 21, 2000
Link: http://www.w3.org/TR/xexpr/
Source Author or Organization: eBusiness Technologies, Inc. (eBT)

XML Expression Language (XEXPR) is a scripting language that uses XML as its primary syntax and is designed to be easily embeddable within XML documents.

The XEXPR scripting language is expressed in XML, and elements of the language are themselves XML tags. The name is not an acronym, but a pun on SEXPR (S-expression) from LISP.

Currently, client-side scripting languages used to build programmatic logic into a document can cause parsing issues that should be avoidable by employing an XML compliant language for client side scripting purposes.

The grammar for the XEXPR language cannot be expressed completely in a Document Type Definition (DTD), because DTDs assume a fixed vocabulary (or fixed set of tags), and the XEXPR language allows arbitrary definitions to occur. (This means that a document with arbitrary XEXPR embedded within it cannot be validated against a DTD unless the DTD is extended to include definitions of all the tags found in the expressions.)