XIST 是一个可扩展的 HTML 和 XML 生成器，同时包含一个 XML 解析器，使用很简单的 Python 树 API，每个 XML 元素类型都被映射到 Python 的类中。你可以把 XIST 当成是面向对象的 XSLT。
XIST 4.10 改进记录：
- UL4 templates can now be used as functions via the <?return?> tag.
- The built-in UL4 functions are now real objects that can be passed to templates as arguments.
- Lists in UL4 support the methods append, insert, and pop, and dictionaries support the method update.
- Line feeds and indentation in the literal text for UL4 templates can now be ignored via an additional constructor argument