Editing the .xml File to Define Control Flow
You can click the Source tab in the editor to see the XML source. You also can edit the source there.
Errors in XML syntax are underlined with a red squiggly line, and there is also a red box in the right margin. You can see a description of the error when you hold the cursor over the box or over the code that contains the error.
You would probably want to edit the XML directly only in certain cases. For example, you may find that cutting, pasting, and editing blocks of code is easier for you than drawing and labeling elements on the diagram.