The image shows the OnAlarm dialog box. The General, Annotations, and Skip Condition tabs display at the top. Below this are the For and Until radio buttons:

For both For and Until settings, in addition to specifying a time using the controls just described, you can define an expression by selecting the Expression option and entering it into the Expression field. Alternatively, you can click the XPath Expression Builder to create an expression.

Below this is the Expression field. At the bottom are the Help, Apply, OK, and Cancel buttons.