A portable electronic device is provided comprising a user input device capable of adopting at least three pre-determined positions, each of which enables an associated function to be actuated, and of adopting two pre-determined positions simultaneously. Also described are methods of determining the visibility of a patterned substrate. The method also includes, using IM, obtaining presence information on the discovered network devices from the discovered network devices and, using the presence information on the discovered network devices from the discovered network devices, maintaining presence data associated with the discovered network devices. The filtrate is then added back to the main process. The gauge can be displaced in the self-locking threading to a locking position, the locking position then being marked and compared with a reference locking position. For both 2\xd72 pixel blocks, no pixel is treated for 2-bit LSBs being 00.