A system and method are provided for enabling instant messages to be exchanged between mobile devices, in particular where a mobile device has access to information pertaining to another mobile device. The first cassette has at least one of the front and rear mating interfaces being different than the front and rear mating interfaces of the second cassette, respectively. by a process comprising: preparing an aqueous or organic solution containing three or more cations; preparing an alkaline solution; slowly combining solutions and to cause the co-precipitation of the cations in the form of hydroxides; washing the precipitate containing the hydrotalcites with water, until removal of the non-precipitated ions; drying; and calcining the hydrotalcites. The first contact plug is formed in the first stepped portion. The respective order identifiers are updated as transactions are processed. At least one layer of the multilayer transfer gate electrode is made of at least two impurity doped amorphous silicon films of different impurity concentration.