Extending XSL

One of the stated goals of the XSL effort is extensibility. Although the original Proposal for XSL of August 1997 described a mechanism for using script to extend the transformation capabilities, the December 1998 Working Draft does not yet provide any details on what the final extensibility mechanism will look like.

The Microsoft® Internet Explorer 5 XSL implementation includes a scripting mechanism similar to that in the original proposal. This mechanism is subject to change when the XSL Working Draft is updated to include an extensibility mechanism, and its use should be avoided when authoring style sheets compliant to the XSL Working Draft.

The scripting mechanism in Internet Explorer 5 provides very limited capabilities:

Generating values through calculations on the source document, such as item numbers, unique ID attributes, formatting of custom data types, and totals. See Calling Script During Transformation
Minimal changes to the transformation process. See Influencing Transformations Through Script

The scripting mechanism supported by Internet Explorer 5 affects only the transformation process. These scripts are executed at transformation time and are entirely separate from display-time scripts in the resulting HTML page. Run-time scripts such as the <SCRIPT> element are not executed by the XSL processor, but instead are passed through and executed by the browser. For hints on generating display-time scripts using XSL, see Generating Dynamic HTML.