In an input unit arrangement use is made of an input unit in combination with a mouse pad, which is provided with a position-coding pattern which codes coordinates for a plurality of positions on the mouse pad. Areas on the mouse pad are provided with subsets of the position-coding pattern which are dedicated to different functions. The input unit can be caused to optically read the position-coding pattern, whereupon the input unit arrangement decodes the positions that are coded locally on the mouse pad. By placing the input unit within the various areas (110-120) on the mouse pad, a user can make the input unit arrangement carry out various functions, such as automatically switching from a mouse function, in which a cursor is controlled on a display on the basis of the decoded position, to an input function, in which information via the input unit is inputted into an electronic device, such as a computer, telephone, PDA etc. A method for controlling the input unit arrangement is also described, as is also use of an absolute position-coding pattern.