You can use XPath expressions to define the context for a statement or to define conditions to transform and filter the data. The function library in the expression editor is standard for the W3C XML Path Language.

When you click the

Expression Editor

button in the input, condition, or output property of a statement, the expression editor appears. The following image shows the expression editor:

You can add functions to the expression by clicking

Add

next to the function that you want to use. You can also type in the expression manually. To validate the expression, click

Validate

.