The outer contour is always considered at planes. When activating "Inner contours" these are considered in addition. That means for example, only those parts are found where the same number of holes is given and where the inner contours are similar, that for each contour in the search part an equivalent hat to be found.
You can find information on partial searches in general under Section 3.1.6.4.10, “ Partial search ” in ENTERPRISE 3Dfindit (Professional) - User.