A controller of a network control system for configuring several middlebox instances is described. Each of the carrying devices includes an endless rotating member and plural unloader pads, the endless rotating member having a plurality of first pad attaching portions at intervals in a rotational direction, on which the unloader pads are detachably attached by sliding the unloader pads in a direction orthogonal to the rotational direction. The calculation of tangential misalignment may be the result of a direct measurement of the tangential misalignment, or may be converted from radial misalignment data. When focusing from an object at infinity to an object nearby, the third lens group is moved toward the object side. The user interface also provides a first on-screen list display zone for showing results of the search performed by the search engine and a second list display zone for showing the results from the hierarchy related to the results shown in the first display zone. One method includes capturing a first image of an iris using a first sensor, capturing a second image of an iris using a second sensor, and determining whether the iris in the first image matches the iris in the second image based on characteristics of the first sensor and the second sensor and image quality of the first image and the second image.