Of course, you can also write the XPath expression yourself. By right-clicking on the "href" input field you can open a popup menu with XPath terms. If you choose a term, it will be written into the "href" input field.
The "Check" button allows you to check the XPath expression currently in the input field. The nodes pointed to by this XPath are selected in the tree view. If the XPath expression should not be correct, an error message from the XPath parser is echoed in the console.
Choose with the radio buttons to the right of the "Start" button, whether you want to query -find out whether a certain action can be executed under the stated conditions- or execute -actually execute the action- the document.
Choose "Policy Viewer" and "Status Viewer" from the "Tools" menu to open a panel that shows the policy and the status associated with the target XML document, respectively.
Choose "Access Request Viewer" and "Decision List Viewer" from the "Tools" menu to open a panel that shows the policy, the status, the access request and the decision list, respectively, for the most recent query.