Domain Discovery Component: The domain discovery is performed
by traversing a query tree, which is constructed from preknown
attributes. For example, “PI State” in Figure 1a is preknown
because all the 74 different domain values are available
on its drop-down menu. Other pre-known attributes include radiobuttons,
check boxes and so on. A more general case without any
pre-known attributes was discussed in our work [4].