ZK User Interface Markup Language (ZUML). The UI declaration language for ZK framework.
zul is the XML based UI declaration language for ZK framework. Also known as ZK User Interface Markup Language (ZUML).
zk is an open-source Ajax framework for modern Java web applications. zk uses two ways to compose UI: XML-based approach and pure-Java approach.
zul relates to the XML based approach. Each XML element instructs ZK Loader to create a component. Each XML attribute describes what value to be assigned to the created component. Each XML processing instruction describes how to process the whole page, such as the page title.