The YvetteML language is used to control the activity of YML. The main roles of the language is to describe component and execution. However, the language allows to control most aspect of a YML installation. This section focuses on the control provided to the user to manage the creation of an application. Instead of the content of tutorials, this section does not shows many example but describe the behavior of any aspect of the language. Most of the language is pure XML, but to make the writing of application description of application graph more human friendly, we use a dedicated language embedded in XML.